How have folks handled scheduling for shift workers?

We have a group of video editors who have fairly irregular schedules. They can work up to 5 days a week on any combination of Monday to Sunday and either morning or evening shifts on those days. Random example:

M T W T F S S

9-5 | off | 9-5 | 4-12 | off | off | 9-5

While we do our best to create predictability for them, there and our schedules mean that the above could be totally scrambled for the same person the next week. We schedule a month to six weeks out and there about 15 editors. We'd like to move to a model where we can use the resource planning elements of WF but it's a show stopper for us if we can't get an accurate picture of how many editors we have available when.

I imagine others most have similar shift type workers, I'd be very grateful to hear how you've handled capturing their availability in the system.

Thanks.

Michael