How To Create A Pop-up Message At Login

My company wants to create a pop-up message that will activate everytime a user logs into Groupwise. The message is for legal mumbo-jumbo. The message would have to be acknowledged prior to continuing with the login.
I am looking to activate thisfrom the server side so that I don’t have to touch every desktop.
Any suggestions?
Do you know of any Groupware developers that might be able to create this?
-MLevy