I think you need the "E" model switch as the "P" is for four wire humbuckers.
http://www.stewmac.com/shop/Electronics,_p...84.html#details
What I do is number the lugs on the pots 1,2,3 with permanent marker from left to right and do the same with the Mega switch lugs.
Remember the pot connections are shown from the back (IE. with the control shafts pointing away from you).
Then its a matter of connecting the wires to the corresponding numbers.
Firstly I would download the full wiring diagram and paste it into word so you can enlarge it and print it out.
Then I number the pots and switch wires on the schematic and then you can study it and follow where each wire goes and color code them if needed. This will get it clear in your mind how to read the schematic and make it easier when it comes to soldering.
So your hot wire on your humbuckers are green and coil tap red/white with ground black.