I've just run a flowing hose water over my engnie before and nothing has ever gone afoul. Here's what I do:
Put on a pair of latex gloves and then take an old tube sock and stretch it out over one arm. Then fill up a cup, like one of those red party cups, with foam engine degreaser. Dip your sock hand in there and scrub away the dirt from your engine and related areas. Then, if you're afraid to hose it down, fill a watering can up with warm water and pour it over the areas to wash them off.
I drive a 78 Trans Am and the wiring in that thing is downright terrifying. There are exposed connections and electrical tape everywhere, but even then, I've never had a short or any such problem doing it this way. As long as you unhook the battery and make sure everything has time to dry, you'll be alright.