See these articles on creating your own vbulletin php page -
How to create your own vBulletin-powered page! (uses vB templates) or
[How-To] vBulletin API Basics: Creating Custom Pages & Misc.
Once you have created the php page, then follow the instructions in the thread you linked to and then you can put $rss2_output in your template to spit out those lines. Or, you can not use a template and instead do the echo directly in the page as stated in the thread.