Per my understanding the process is highly controlled and reviewed, so with that being said then all you need to do is coopertate and submit patches or new moduels. If you are comfortable enough with the kernel components then you download the latest kernel snapshot from git and start making and submitting your revisions.

I found a guide called "HOWTO do Linux kernel development" at http://lwn.net/Articles/160191/ which should give you same good starting instructions.

An index of the kernel trees and quick instructions for downloading the trees using git are located at http://git.kernel.org/.

Just another site to look at, Kernel Newbies, I've found some useful info there at times.

http://kernelnewbies.org/