Multisite Config Hack

First, let me say I don't have access to httpd.conf just a user root and ./public_html
Looks like I mainly do this with .htaccess (whether hand written or done in cP seems the same).
I tried real hard to get different settings.php loaded. I use sub domains ie:

sub1.domain.com
sub2.domain.com
sub3.domain.com

point to the sub-folders
sub1
sub2
sub3

Here's my settings.php for each site:

sites/sub1.domain.com/settings.php
sites/sub2.domain.com/settings.php
sites/sub3.domain.com/settings/php

But I couldn't get it to work. The only config used was /site/default/settings.php

I know this was being loaded as I could change the database it loads. In fact, it seems to absolutely require a db name not a blank one as in default.settings.php

I'm also unclear what the.. four settings.php files should have as their $base_url ="??" if any. The more solid settings the better. Would I use these in the four settings.php files (including default):

sites/default/settings.php with -> $base_url = 'http://domain.com/'; (which is where the main drupal is installed)
sites/sub1/settings.php with -> $base_url = 'http://sub1.domain.com/'; (or..)
sites/sub2/settings.php with -> $base_url = 'http://domain.com/sub2/'; (or..)
sites/sub3/settings.php with -> $base_url = 'http://domain.com/';

I prefer using subdomains because I want to (inevitably) scale very seperate topics desering their own subdomain to begin with I believe.

Thje only thing I have been able to do to get this working so far is to end up loading a different bootstrap.inc file for each site at least for now. ie:

http://sub1.domain.com/ redirects to (done by cP actually) ->
http://domain.com/sub1/.htaccess which loads custom file:
/index-sub1.php which loads custom file:
/includes/bootstrap-sub1.inc which loads custom file:
/sites/sub1/settings.php
phew.

Bottom line, is I have to hack a seperate bootstrap.inc for each. I'll re-read everything I can find on the matter again and try to figure out where I'm going wrong. I'm thinking there's a url translation proplem somewhere. Perhaps if I can remember how to script the output of variable values to file would help. I only have ftp execute or http execute of scripts available. It'll be something trivial.. I just know it. Grrrr.