I have done these for local friends before and don't feel comfortable doing them for people that I cannot directly support, since if your doing a MS3X and I'm not holding your hand through it all you should build it as well to understand what it all does.
With that said a while back I put together a connection table to go to the Break out board from the two DB-37 MS3/X connectors which all three are supplied by DIYautotune.com that Paul Lohr posted above. I cant remember if I detailed every single connection but it should be 99% complete as I can make it at this point. This will be the first time I release this document to the general public and is definitely a beta, and if you have questions or request of info I should add please let me know and I will do the best I can to make it more user friendly. I also have the wiring information for COP coil wiring in the document if anyone chooses to ditch the junk stock coil and module like I did, it only costs the price of 6 junk yard GM "LS" coils ($20 at my local yard when I find them) so for me it was a no brainer...
For those of you who are not Excel inclined In the document I have hyperlinks (IN BLUE), and any boxes that have a red arrow in the corner will pop up text notes if you hover over them with information that I thought might help the average Joe understand what it is for. Also there is a legend in the top right corner to help explain (or confuse you more! LOL).
As a disclaimer if you use my information published I am not liable for any damage you do to ANYTHING on your car. Though I am fairly certain I have published everything correctly some people on here would run a 12 gauge wire from direct battery power to ground if it was written to do so... USE AT YOUR OWN RISK!
Have fun and happy Megasquirt boosting!
,Dan