Although this is a way dead topic, it is worth noting that the rules are a little different from the last post in 2011.
Every quarter you go on the Hub and indicate your availability. You go week by week and identify the days and times you are willing to work. Every week you check your schedule and you may be scheduled in the times you marked as available, but it is not guaranteed. You can also pick up available shifts that you are trained for. There is the Extra Hours Hotline, where the company posts shifts that it was not able to pre-fill and there is a module where people post shifts they would like to give away. You can work 40 hours a week in theory, but keep in mind that seasonal and extra hours shifts are the ones they use to fill in the schedule, so in some areas there are a lot of less-than-8-hours shifts that are the leftovers after all the full-timers are scheduled. Like a 3 hours shift to help with stanchions at the parade. At places like the Sports complex, many of the cast are seasonal (retired snow bird types) who work full time during a particular sport season and then go home. Eventually there is a weekly hours cap, but I don't think you would hit it.
Now, this is the big change... to remain employed you must maintain 160 hours worked in a rolling one-year period, checked quarterly. I'm making the dates up, but the idea is that between 1/1/14 and 1/1/15 you have a total of 160 hours worked, between 4/1/14 and 4/1/15 you have a total of 160 hours worked, and so on. It is not 160 hours EACH quarter, its a rolling period. So if you work all your hours in one quarter they will all fall off at the same time a year later and leave your hours bank empty if you haven't worked again to refill it.