Ok so I wanted to post a follow-up since I got it to work (for the most part at least). All redirects in the htaccess code below under "# 301 Redirects for indexed URLs from old site" work except for the ones toward the bottom that start with "index.php?page="—which as you’d suspect go to the home page of the new MODx site. Not ideal but at least they go somewhere from the SERP. On that note, if anyone reading this knows how to fix these remaining redirects please chime in! I’m assuming it’s a syntax thing with htaccess and I’m definitely a novice when it comes to htaccess. At any rate, hopefully this post helps some other people in the same situation.
# For full documentation and other suggested options, please see
# http://svn.modxcms.com/docs/display/MODx096/Friendly+URL+Solutions
# including for unexpected logouts in multi-server/cloud environments
# and especially for the first three commented out rules
#php_flag register_globals Off
#AddDefaultCharset utf-8
#php_value date.timezone Europe/Moscow
# For security reasons, Option followsymlinks cannot be overridden.
#Options +FollowSymlinks
Options +SymLinksIfOwnerMatch
RewriteEngine On
RewriteBase /
# Fix Apache internal dummy connections from breaking [(site_url)] cache
RewriteCond %{HTTP_USER_AGENT} ^.*internal\ dummy\ connection.*$ [NC]
RewriteRule .* - [F,L]
# Rewrite domain.com -> www.domain.com -- used with SEO Strict URLs plugin
#RewriteCond %{HTTP_HOST} .
#RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]
#RewriteRule (.*) http://www.example.com/$1 [R=301,L]
# Exclude /assets and /manager directories and images from rewrite rules
RewriteRule ^(manager|assets)/*$ - [L]
RewriteRule \.(jpg|jpeg|png|gif|ico)$ - [L]
# 301 Redirects for indexed URLs from old site
RewriteRule ^en_US/contactform.html http://www.thefrenchacademy.org/contact/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/administration.html http://www.thefrenchacademy.org/administration/ [L,NC,R=301]
RewriteRule ^en_US/immersion/ressources.html http://www.thefrenchacademy.org/why-immersion-resources-and-links/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/testimonials.html http://www.thefrenchacademy.org/testimonials/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/philosophy.html http://www.thefrenchacademy.org/philosophy/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/press-releases.html http://www.thefrenchacademy.org/news/ [L,NC,R=301]
RewriteRule ^en_US/news.html http://www.thefrenchacademy.org/news/ [L,NC,R=301]
RewriteRule ^en_US/immersion/faq.html http://www.thefrenchacademy.org/why-immersion-faqs/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/parent_community.html http://www.thefrenchacademy.org/parents-community/ [L,NC,R=301]
RewriteRule ^en_US/elementary/staff_el.html http://www.thefrenchacademy.org/french-elementary-school-staff/ [L,NC,R=301]
RewriteRule ^en_US/immersion/benefits.html http://www.thefrenchacademy.org/why-immersion-benefits/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/after_school_activities.html http://www.thefrenchacademy.org/french-elementary-after-school-activites/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/schedule.html http://www.thefrenchacademy.org/french-elementary-school-daily-schedule/ [L,NC,R=301]
RewriteRule ^en_US/admission/application.html http://www.thefrenchacademy.org/admission-application/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/links.html http://www.thefrenchacademy.org/why-immersion-resources-and-links/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/curriculum.html http://www.thefrenchacademy.org/french-elementary-school-curriculum-and-classes/ [L,NC,R=301]
RewriteRule ^en_US/about_fam/employment.html http://www.thefrenchacademy.org/employment/ [L,NC,R=301]
RewriteRule ^en_US/elementary/classes_el.html http://www.thefrenchacademy.org/french-elementary-school-curriculum-and-classes/ [L,NC,R=301]
RewriteRule ^en_US/preschool/classes_mat.html http://www.thefrenchacademy.org/french-preschool-curriculum-and-classes/ [L,NC,R=301]
RewriteRule ^en_US/admission/process.html http://www.thefrenchacademy.org/admission-process/ [L,NC,R=301]
RewriteRule ^en_US/about_fam http://www.thefrenchacademy.org/about-us/ [L,NC,R=301]
RewriteRule ^en_US/admission/tuitions.html http://www.thefrenchacademy.org/admission-tuition/ [L,NC,R=301]
RewriteRule ^en_US/immersion/why-french.html http://www.thefrenchacademy.org/why-immersion/ [L,NC,R=301]
RewriteRule ^en_US/news/27/82/Unexpected-visit.html http://www.thefrenchacademy.org/unexpected-visit/ [L,NC,R=301]
RewriteRule ^en_US/news/21/82/Enrollment-2010-2011.html http://www.thefrenchacademy.org/now-accepting-applications/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/administration.html http://www.thefrenchacademy.org/administration-fr/ [L,NC,R=301]
RewriteRule ^fr_FR/contactform.html http://www.thefrenchacademy.org/contact-fr/ [L,NC,R=301]
RewriteRule ^fr_FR/immersion.html http://www.thefrenchacademy.org/pourquoi-limmersion/ [L,NC,R=301]
RewriteRule ^fr_FR/application.html http://www.thefrenchacademy.org/dossier-dinscription/ [L,NC,R=301]
RewriteRule ^fr_FR/admission/process.html http://www.thefrenchacademy.org/processus/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam http://www.thefrenchacademy.org/a-propos-de-nous/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/press-releases.html http://www.thefrenchacademy.org/nouvelles/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/parent_community.html http://www.thefrenchacademy.org/communaute-des-parents/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/links.html http://www.thefrenchacademy.org/ressources-pour-limmersion-et-liens/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/curriculum.html http://www.thefrenchacademy.org/ecole-elementaire-programme-et-les-classes/ [L,NC,R=301]
RewriteRule ^fr_FR/immersion/faq.html http://www.thefrenchacademy.org/foire-aux-questions/ [L,NC,R=301]
RewriteRule ^fr_FR/preschool/classes_mat.html http://www.thefrenchacademy.org/la-maternelle-programme-et-les-classes/ [L,NC,R=301]
RewriteRule ^fr_FR/immersion/why-french.html http://www.thefrenchacademy.org/pourquoi-limmersion/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/philosophy.html http://www.thefrenchacademy.org/philosophie/ [L,NC,R=301]
RewriteRule ^fr_FR/about_fam/testimonials.html http://www.thefrenchacademy.org/temoignages/ [L,NC,R=301]
RewriteRule ^fr_FR/admission/application.html http://www.thefrenchacademy.org/dossier-dinscription/ [L,NC,R=301]
RewriteRule ^fr_FR/news/3/82/New-website.html http://www.thefrenchacademy.org/nous-allons-de-cet-ete/ [L,NC,R=301]
RewriteRule ^fr_FR/home.html http://www.thefrenchacademy.org/accueil/ [L,NC,R=301]
RewriteRule ^fr_FR/elementary/classes_el.html http://www.thefrenchacademy.org/ecole-elementaire-emploi-du-temps-quotidien/ [L,NC,R=301]
RewriteRule ^index.php?page=links&hl=en_US http://www.thefrenchacademy.org/why-immersion-resources-and-links/ [L,NC,R=301]
RewriteRule ^index.php?page=employment&hl=en_US http://www.thefrenchacademy.org/employment/ [L,NC,R=301]
RewriteRule ^index.php?page=ressources&hl=fr_FR http://www.thefrenchacademy.org/ressources-pour-limmersion-et-liens/ [L,NC,R=301]
RewriteRule ^index.php?page=press-releases&hl=en_US http://www.thefrenchacademy.org/news/ [L,NC,R=301]
RewriteRule ^index.php?page=process&hl=en_US http://www.thefrenchacademy.org/admission-process/ [L,NC,R=301]
RewriteRule ^index.php?page=faq&hl=fr_FR http://www.thefrenchacademy.org/foire-aux-questions/ [L,NC,R=301]
RewriteRule ^index.php?page=administration&hl=fr_FR http://www.thefrenchacademy.org/administration-fr/ [L,NC,R=301]
RewriteRule ^index.php?page=press-releases&hl=fr_FR http://www.thefrenchacademy.org/nouvelles/ [L,NC,R=301]
RewriteRule ^index.php?page=contactform&hl=fr_FR http://www.thefrenchacademy.org/contact-fr/ [L,NC,R=301]
# For Friendly URLs
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]
# Reduce server overhead by enabling output compression if supported.
#php_flag zlib.output_compression On
#php_value zlib.output_compression_level 5
# Redirect famn.org domain (all URLS) to thefrenchacademy.org
RewriteCond %{HTTP_HOST} ^famn\.org$ [OR]
RewriteCond %{HTTP_HOST} ^www\.famn\.org$
RewriteRule (.*) http://www.thefrenchacademy.org/$1 [R=301,L]
