You should be able to create a standalone harnless with a new fuse box set up. I usually use a Painless 7 circuit Aux Fuse setup. That usually is enoough for a basic setup. If you need more circuits, the setup is expandable by adding another 4 circuit block on.
I then setup a another fuse and relay setup for the Elecrtical Fan if your using them. http://www.summitracing.com/parts/PRF-70207/ http://www.summitracing.com/parts/PRF-30002/
see my project post #98 and #100 for what I did.. https://ls1tech.com/forums/conversio...-ls1-a4-5.html
If your not good with wiring and can not find anyone local to help, you can look up one of the sponsor vendors to convert your factory harnless or buy a new custom one. But it is a good thing to learn about the EFI and wiring, it usually takes a few hours for the 1st timers, just need to read the FAQ and get the pin out of your year/model harness.