The first thought is "Why?' Next thought is be sure to use large gauge wire and high amperage switches and relays, etc. Also make sure there's a timer or some other safety to keep you from forgetting they're on. I'm sure you have a good reason to want to do this, is it because the system quit working?
Do not intend to rewire the 'SYSTEM', just the pre-fab harness part. They are about $70 and a #10 stranded copper wire would be a LOT less. The question I have is How to do it. There are two wires to the Harness 'part' and I was wondering what to connect to what and the most effective manner.