[dartho]

a plugin on style_fetch hook with an execution order of say 10 should do it - something like:

PHP Code:

if ($vbulletin->userinfo['userid']==x)
{
  $styleid=y;
} 


or if multiple for users:

PHP Code:

if (in_array($vbulletin->userinfo['userid'], array('x1','x2','x3')))
{
  $styleid=y;
}