Thanks for the reply, BobRay. I literally found the solution to my problem about 2 minutes before your reply. Funny how that works!
I actually found what I needed to do in the Evo 1.0 docs at:
http://rtfm.modx.com/evolution/1.0/administration/friendly-url-solutions
"If you're working off of virtual domains and have a preview for development or while waiting for DNS updates to occur such as accessing your site through
http://10.0.0.1/~myacct, the rewrite rule should be written as follows. Don't forget to change it back when you go live."
I changed my RewriteRule to "RewriteRule ^(.*)$ /~myacct/index.php?q=$1 [L,QSA]"
(obviously replacing "myacct" with my MODx site's account name)
I'm facepalming at myself for spending so long on this problem when the solution was staring me right in the face (URL bar)! Maybe I missed it in the Revo docs but I think that tidbit of information should definitely be put in if it's not there already (just in case other people are as unfamiliar with .htaccess files and rewrites as I am
).
Now I have to remember to change it back when I set up the domain name... lol.
Thanks to all who checked this thread!