Unfortunately, only document libraries expose an event hook for custom actions driven by custom code.
(see msdn.microsoft.com/.../tsptDocLibEvents.asp for info)
Here's the info for manipulating the toolbar:
msdn.microsoft.com/.../tsptCustomToolbar.asp
Then, check the link below for info on using the object model to add elements to lists:
msdn.microsoft.com/.../...ingDeletingListItems.asp