Tim, if you are looking for some guidance on the Megasquirt, then you need look no further than this website. We have a topic here: http://www.locostusa.com/forums/viewtopic.php?f=27&t=12117
Of course there are many other sites with engine-specific help on implementing the MS. But for familiar people, this would be a good place to start.
The MS is a great project for us "Locosters". I am running a MSII box with no additional adapter boards. I just was careful in my wiring and added a few external relays and diodes . It doesn't need to be as costly and complicated as some would suggest.