The problem is the whole assembly holding the original headband on is plastic (Thin plastic at that) including the "Rivet" (half plastic) that holds the original headband to the wing.
I did see a replacement guide where someone took some pliers and bent the metal part of the rivet up and pulled it apart, but even then, it's not going to go back together.
I opted for just drilling mine out.
The problem with that is, the plastic is so thin it tends to melt together when you drill it so you may have to get creative to separate it afterwards.
You can also check out this thread.
http://www.head-fi.org/t/655345/akg-q701-headband-replacement
and this imgur
http://imgur.com/a/VWSkq
for more ideas.