How can I compile only one module in Debian?

I have a Thrustmaster Dual Trigger 3-in-1 gamepad (USB ID 0x044f:0xb323) that is not covered in hid_tmff module. I've tested with xboxdrv and it seems to accept the same force feedback commands used with Thrustmaster Dual Power (but axis/buttons are reported differently, so modifying xboxdrv is more complex).

I've "patched" hid_tmff (found in kernel sources, under drivers/hid path) including my USB ID and same data as the other gamepad, but don't know how to compile only that module and make it work with my stock kernel (when I do insmod, it complains about bad module format... different kernel versions?).

Another question... how can I report my "ultra-complex patch" so it could become official in later kernel releases?

If you have the source code for the driver, then you can use module-assistant to build and install the module for you. You'll need the header files for your kernel and (maybe) the kernel source code but m-a can go and get them for you. It will also load the module for you.
cheers,
jdk