ETA: or...
There's a manual page that shows how to include the output from an external php script:
http://www.vbulletin.com/docs/html?m...rsion=30806601 search for "Including External Files".
Or if you want to take the opposite approach and make your script a custom vBulletin page there's an article that shows how to do that:
https://vborg.vbsupport.ru/showthread.php?t=62164