I haven't seen an adapter to allow the flat surface. You might find a cell phone headset with the right plug size, but I haven't done that with the 360. I've used the 360 wireless headset for a few years now, it helps avoid a lot of problems. If you do any pc gaming, the wireless receiver for pc picks up the headset as well as the controller. Very nice for pc gaming as well as the 360.
Looking at Amazon, this Plantronics has the right plug. Wired but inexpensive:
http://www.amazon.com/Xbox-360-Over-...171969&sr=1-10