Check the technical articles on the Pelican site. I wrote an article years ago about converting to the 924 switch and to the electric pump.
Esentially, you have to take the white plastic wire holder from the old switch and move it to the new switch and you will be left with 2 extra wires that can be used to control the pump in the front trunk. (You have to mount the pump up front under the washer bottle.
Here's the link...
http://www.pelicanparts.com/techarticles/914_electric_washer/914_electric_washer.htm