If you're going to split & phase-switch & such with a 5 way, you will probably need a Super 5 way.
If you're jazzmaster has a Tele type control cavity, you will probably need a narrow Super 5 way.
I used this one in my current Tele to get 3 pickups with middle & bridge in both series & parallel.
I got mine here. It is probably available elsewhere, but it is not the same as the Super 5 sold by Stew-Mac.
http://www.toneshapers.com/ToneShaper-5-Way-Narrow-SuperSwitch-P2773.aspx
:rock-on: