The better you've planned the faster you'll be. But take enough time to make a clean install. If all wires are in position connect the empeg without fixing the docking-sled in it's final position - try if the empeg works, first.
See to have all connectors and enough (and the correct) cables you'll need. It sucks if you are installing the unit and you recognize that you'll need another cable or connector you don't have at this time.

Good luck and much fun!
(I like those car-installs so much

TeeMcBee
Got my Mk2! # 080000143