I've got a jackson kelly that has only a single volume pot, but has a three way switch. I'm thinking of putting an EMG 89 in the bridge and a 60 in the neck. could i wire a push/pull pot to work the coil tap or do i need to wire a 5 way rotary?

Usually, when you buy EMG pickups, the wiring harness comes with them. You should talk to EMG, or an authorized dealer. They are made to work with their own electronics. If EMG doesn't have the options you are wanting, try Bartolini. They will custom make you a setup.