This link should give all the details you need for hooking up the MPGuino.
CRX Community Forum • View topic - MPGuino
My best advise on wiring mods is to never touch the stock wiring under the hood unless there is no alternative. Your splice at the injector is a major long term reliability problem that will eventually fail. It's much better and easier to make the splices at the ECU.
I read your build thread and have a couple comments.
If your fuel line splice is on the low pressure return line it would probably only become a problem during an accident. If the splice is on the high pressure supply line it's incredibly dangerous and should be fixed properly before further driving.
For your interior restoration keep in mind the HF did not come with a cargo divider to save weight. The back end is mostly open on the stock HF.
You mentioned buying an OEM muffler for $75. Is that a genuine Honda OEM muffler for an HF or is that something else like an OE replacement muffler or DX muffler?
Mike