There are several folks on this forum who are far more knowledgeable about rigging a second help than I am.
When I had my BF 225 installed, I used the dealer to set up a second helm, so I can just describe what I have.
First you will need a different wiring harness and a different key switch panel for each helm. Each of those key switch panels will have an extra switch that allows you to switch from one panel to the other - actually to take control of the electronics, depending on which helm you are using. It was explained to me that it's very important to do this right or you can easily burn up your engine electronics.
The second hydraulic helm is fairly simple and diagrams for doing that are all over the internet. Just make sure you have the proper check valves in the hydraulic lines.
As for the throttle and shift controls, how that is set up depends on what you currently have. I opted to keep my old Morse controls and cabled the main control into the aft control, then on to the engine. That setup s not optimal IMO. I would recommend having each control cabled straight to the engine.
