I installed the switch today. I ordered the ECS Euro Switch M3 chrome, $119.95 including shipping:
http://www.ecstuning.com/BMW-E92-M3-...tch/ES1899562/
I used a set of Harbor Freight auto trim tools (on sale for $6.49) and levered the upper trim piece out first gently, then the lower assembly. I saw the lip on the lower assembly and belive if you can remove the upper (it comes out slowly) that is an easier install, but YMMV.
Picture below is just after the upper trim was removed, showing old switch in place.
Tested and works great, DAMN those lights are bright lol.