I just found this old post so am bumping it.
I cook mushy peas, not the fast soak ones, but the regular ones that you soak overnight. I do them three or four boxes at a time, then after rinsing them the next day I do them in my slow cooker/slowcrock. I find boiling them sometimes pops the skins off but the slow cooking is bang on right. It takes much longer but you can do them on low and go out. When cool I pack them in 1 cup size servings , they freeze very well if cooked right then when I need a packet to go with fish and chips, I nuke them. Works perfectly.