Enable/disable modules based on Virtual Site

After researching many modules to make my website do what I want to do, I found virtual sites... which is great to change themes and do some tweaking when certain conditions are met..

To Summarize:
- I got the condition set and working for one of my virtual sites
- Now I need to disable a certain module.. which I think virtual sites can do it easily since it can change the themes and menus easily :)
- But I have no Idea how to use virtual sites to input the SQL command to disable the module! How to write a custom plug-in to let user key in PHP codes or SQL to change the database?

This link: http://drupal.org/node/51216 tells me that to disable a module I just need to run the SQL command:
UPDATE `system` SET status=1 WHERE name='example';

I'm so close to get what I want to do... please help... !!

Thanks ^^