We started self-scheduling several years ago and it can work real good when you have enough staff. When your staff #s are at the bare bones, it is difficult, everyone is stressed out and no one wants to be the first one to give on anything. Our manager started doing our schedule again about 3 months ago and we are finally getting to trial the self-scheduling again.
Get your rules figured out first. AND, PUT IT IN WRITING, with lots of copies around, so no one can dispute what was said and it won't disappear (and ok the rules with your manager so you have the boss's backing if someone chooses to complain). Who is working what weekends? We have to work 3 mondays or fridays, or any mixture thereof every 6 weeks. You need to figure out your holiday schedules early, so that you can all be planning and see who wants to switch, if any do (we started by looking at who worked what last year and switched it for this year). Determine how many people need to be on each day and let everyone know that if everyone doesn't help to make the minimum staff/day then changes will be made before the final schedule is put out. Our charge nurse ultimately made sure the schedule was filled in and shifts were evenly distributed. It helped us to all "own" the process by taking turns doing the proctoring. It made everyone realize just how much work went into getting a schedule to work. It also helped to keep track of how many changes each person made to get the schedule finalized, you could easily tell who wasn't helping and that person usually didn't like it that you'd started keeping up with how many changes they'd made. And, yes, we all need a bend in the rules now and then, but you really need to enforce them, or one or two will have the schedule they want all the time without making any changes, and it will cause resentment in those who make several changes for the unit.
Good luck on getting it to work!!! And, remind everyone that if they don't make it work, that someone else may be doing their schedule again for them. That usually puts a little boost into the helpfullness.