i have completely integrated phpmychat with vbulletin on my site. it authenticates via the 'users' table, determines permissions via 'usergroupid' and is also integrated with the gender hack. all commands are working (ie. /kick, /ban, /promote) and has been nicely customized to match the style of my site. come take a look at
http://www.enterthemuse.com/ username/password: test