Hey man
I don't think you realy need plans...its basically just small parts at your local electronic supplier, of course you can use a scrap ECM for its OEM connector.
I would strongly recommend you make one that can be "spliced" into the harness, so you can fire up the car, and check ins/out.
I have used BOB's for many years and always thought that they werte a real overlooked tool, for model specific applications.
Good Luck
Later