I recently went through this same exact excercise. In order to make sure that your motor is working properly and that your wipers are parking, I would spend $20.00 and purchase the rocker switch from Finishline:
Finish Line Accessories
It comes with very clear wiring instructions and you will need to provide power both to the switch and the motor. I purchased one of the newer PRS7 rotary switches and was lucky enough to obtain a correct knob. I installed it in my dash so that it looks correct but it does not work. I mounted the Finishline toggle switch directly above the rotary switch and that is what I use to this day. I have searched and searched and cannot find a rotary switch that works with the two speed motor, parks the wipers that will fit in the dash and accept the correct knob.
Good Luck
