Since Carol Deppe's book 'Breed your own vegetable varieties' and Rebsie Fairholm's pea breeding experiments , that resulted (amongst others) in a red-podded pea all written up in her blog, there has been quite a bit of interest in pea breeding.
It is not that difficult to make the original cross, which will be the start of a new variety. I have bred a yellow-podded mangetout 'Court Estate Gold' with much larger pods than its parent 'Golden Sweet'. Here is a superb video instruction on making a cross by Mike Ambrose from the John Innes Institute.
http://www.youtube.com/watch?v=Pq7-JGRmFBc
Interesting video link - thank you..