You said you don't want to use templates, but this really is the easy way -
How to create your own vBulletin-powered page! (uses vB templates) or
[How-To] vBulletin API Basics: Creating Custom Pages & Misc.
You actually only put html in templates. If you need to do something with php, you put it in the php page and instead of just doing an echo, you assign the results to a variable that you then put in the template.