I have been able to get the AIM add all to work on adding the first name on the list, but not the second.
This is the code I have;
a href="aim:addBuddy?groupName=Darkest+Of+Times&listofscreennames=Fieldz0fJoy,Combat+to+Boot">Add all players to your buddy list.</a
I've checked it against the code you have here and it looks like it should be working. Any ideas?