I've used the CBS wiring module for the heart of the electrics. Great piece of kit after a bit of head scratching!! It does most of what you need (with the exception of a few relays and a few additional live and swithed live terminals) and it does some things that are already available from the BMW engine harness. But once you've got your head around what you want to do what, its fairly straightforward. I've got the cover as well so with a bit of sealing strip around the base it should be nicely splash proof.