I half did it to my car then gave up cos its time consuming and back breaking being bent over the engine bay. I hid a few wires around the edges of the engine around the throttle body and the injectors.
I am sure you could give it to someone to do but I'm not sure how much it would cost.
You can buy a wire tuck wiring harness from the states which is plug and play, I believe and it runs around the engine bay in hidden places. Behind the rocker cover, under the suspension towers and in behind the arches, Across the underneath of the front slam panel, I know the fuse box is easy to hide as it just moves down and bolts on the inside of the wheel arch. There may be a single rubber tube that goes through the engine bay and all the wiring is held within it and just the plug comes out.
Problems? If some electrical connector is plugged in wrong, if a wire frays, if anything goes wrong you wont know what wire comes from where and where it ends up connecting to. So it will be a bit of a maze finding the source of the problem.
Don't think the dash has to come out, if you want to tuck the power steering and abs i believe they move them bits behind the dash. Look up the wire tuck thread on clubrsx.com
