Help with a simple port

[John Stone]

I imagine this is going to be a simple question for you vB whizzes out there!

I wrote a very simple, but useful (well, useful to me) vB 3.0x mod and would like to make it work with 3.5x, but I'm not sure where to put the code.

The old code was in "sessions.php", and it ran once whenever a new user came online, notifying me by email if the user who just came online happened to be a member of a particular user group.

In 3.0x my code came right after this line:

 
{ // see if session has 'expired' and if new post indicators need resetting
 
// HACK CODE
if ($bbuserinfo['usergroupid']==XX)
{ blah blah
}
// HACK CODE

Since "sessions.php" no longer exists, where is the best place to put the code so that it is just run one time each time a user comes online?

Thanks for any help.