i've put in a switched relay to my fuelpump. it sounds hard, but when you get enough info, it's dead easy.
use what's called an "87 relay" it's a 4-prong relay.
like this one
connect like you see the bottom part of the picture, can't go wrong.
and this is coming from an electrical retard.
if you look at my buildthread, you'll see all the wiring i've done. about 90% of the car, and that's just because somebody told me how to do it.
it's really easy actually