I'm sorry I can't speak from exerience but I am facing a simular problem. My pedal doesn't return up and thought that there might be a spring in the mechanism for the pedal to return to the released position. After removing it, I found there seems to be no spring there and went to reinstall it and that's where the trouble began. I spent two hours trying to get the three bolts started that hold it to the side of the truck. I would get the two "easy-ish" bolts started and try the top bold and end up droping it into the assembly and have to remove the whole thing to retrieve my bolt. What ever you do, don't that that assembly off the truck , it won't make removing the cable any easier. I am thinking the spring under the truck pulls the release pedal but it's been too cold/wet to fool around on the ground and since I haven't used the ebrake in such a long time, I am not going to even try to set it with the drum on. Sorry I didn't really answer your question but instead gave you a pointer on what not to do. My guess would be to back off the adjusting nut as far as it would go with the pedal released and that should give you the slack to remove the cable from the keepers. Just a guess though.
