Unfortunately theres nio list of variables although this will help
http://www.vbulletin.com/docs/html?m...rsion=30807603 and maybe more so this one
https://members.vbulletin.com/api/index.html it contains all the api's...etc thats in the vbulletin product.
As i said though, turn on debugging and look at the templates and hooks called, thjat will give you a much better idea.