Ax Alert Rule flow of methods??

Hi ,

I am trying to customise the existing alertrule form which allows us to select a User to whom the alert is sent.

i am working on a functionality that would allow me to send similar alert to an entire UserGroup. I got a lookup of usergroup on the ALert Rule menu.

Can some1 help me with how the User id Event is handled so that i can implement somethin similar to send the alert to a userGroup.

Thanks.