(keep in mind I speaking from my experance in php coding only

)
well..i re read your post, and to my understanding your just looking to have the who's online update when a user is on your site pages. That way you will get the 'real' number of online users.
If you include global.php (from the /forum folder, not /forum/admin) it will check for sessions and do all the work of updating the table. However, im not sure if you can include .php scripts in a .asp page...
if that is so you can have a look at sessions.php (if you already have you know what a mess that file is!

). Ill take a peek in a minute and see if i cant extract the query's for you. For now i must eat breakfast and take a shower