In-between my cheek pad lining and the helmet, using a piece of kitchen sponge as a wind sock and to stop the microphone form picking up vibrations from the helmet.
I put the mic in behind the cheekpad and noticed I still pick up a little windnoise at certain speeds, granted it's fine if i'm going under 40mph. I'm still experimenting with positions to find out what works best for my helmet.
You know, whenever someone picks up wind noise, god kills a kittenI really hope this helps, otherwise I'll try getting one of those dead cats!