Hi Dave_Biscuits I tried to do it your way thought I had found the answer on 12volt .com about how to wire the relays and NOPE.
But I did make a DIY video on how to do it with an aftermarket kit.

Success

https://www.youtube.com/watch?v=K_2z1fFrdhA

Well, it is done I ended up with Keyless remote entry.