Hi, this is quite a bit off topic from stomp boxes, ha ha, but I'll give you some quick info:
1) Look into using a "wah shell", with its internal potentiometer, to gradually increase the voltage to your magnets. Google. This will let you use your foot to sweep forward, like a sewing machine pedal.
2) You can probably get an Arduino and program it to step thru your magnets....at 'voltage = such and such', output 1 is on, then off....output 2 on, then off...see what I mean? Easiest way for you to do this is to get a micro controller and actually PROGRAM the steps. Doing that electronically can be done, but probably is kind of out of your expertise right now, it looks like, if you're kind of lost.
3) find a friend with some electronics background to help you sort it out! Good luck.