Trying to use custom php.ini

I am trying to use a custom php.ini in order to increase max_execution_time. Following the instructions of my Host (pair.com), I
1. copied php.ini and php5.cgi into my local cgi bin
2. tweaked that new php.ini
3. added two lines to modx/.htaccess:
Action application/x-custom-php /cgi-local/php5.cgi
AddType application/x-custom-php .php

Now, when I browse to modx/index.php, I get this error: "The requested URL
/cgi-local/php5.cgi/modx/index.php was not found on this server."

Pair.com support (usually excellent) said "It looks like the script you are trying to run is looking for
"/cgi-local/php5.cgi/modx/index.php", however, that path does not exist because
php5.cgi is not a directory. You are going to need to find where that value is set and make sure to change
it."
I’m such a newbie that I find it hard to evaluate or follow through on that response.
I’d appreciate any recommendations for either getting my custom php.ini to work or otherwise increasing max_execution_time.

For what it’s worth, here is what I know about my setup:
MODx version = 0.9.6.2
Version codename = rev 4077
PHP Version 5.2.6 (running as mod_php --I think, but not sure)
Loaded Configuration File = /usr/local/etc/php5/php.ini
Apache version = 2.2.9
OS = Free BSD 6.2-Release-p1

You are going to need to figure this out with your hosting provider and how they have configured your server.