You can use DPDT, 6-pin switches. You can wire them up straight from battery to fuse to switch to pump, but if your wire runs are more than a few feet and you want to run all three pumps at the same time, you may want to use relays to keep the runs from your batteries to the pump as short as possible. And/or use very large wire. The Simers draw a lot of current, especially when they spike at turn-on. Turn them on one at a time.
Here's way too much info on wiring the switches, along with a relay schematic that most people use. It's a little confusing on the first read through: http://www.wakeworld.com/MB/Discus/messages/65921/150439.html?1082658376
I drilled mounting spaces into the fiberglass next to my throttle arm, but you could also mount them in your dash or make a small box to mount under the dash, or at the drivers feet, etc.
Good luck. You will be very happy when you have it all working right.