With the grind band I'm in we've done numerous splits. Most of them we had never even heard of before we were asked to do it. Everything is arranged through the distro label though, so we actually never even talk to the other band(s) or anything. Doing it yourself I would assume it's just like setting up a show, get in touch with the band(s), tell them the idea and see if they go for it. Pretty straightforward.
~006