Hooking an on enter event to a standard UI element

[lgweaver]

for an add on Enhancement I'm working on I need to hook an on enter event to MainMenuBarMackpackButton but my experaince is limited and I'm having trouble with this. is it even possible to hook an event to a frame the ad don didn't create?

If not I may have to poll the size of MainMenuBarMackpackButton and create an invisible frame over the MainMenuBarMackpackButton and use an on enter event for that frame. For efficient code if I do not need to create a frame I do not want to.