/diy/ - Do It Yourself

I can't stress enough that I am a COMPLETE beginner when it comes to electronics, so bear with me.

I got this neato 8 position switch and thought I could make a/v selector switch of sorts that has four rgb and four component inputs by pulling the board out of my rgb to component converter and cobbling it together with the connectors and the switch. See my really shitty diagram if that didn't make sense.

My problem boils down to a lack of knowledge here (especially about what I need to do in that yellow box): How can I use the switch to control which input is connected to the output? Is there a way to have the switch control a switch that has more pins (ie if the dial switch is turned to 1 it takes the signals from input 1 and feeds them through to the output)?

Another problem is how to tell if the input needs to be fed through the converter or not. In the case of Component video I have Y, Pb, Pr, L Audio, R Audio (5 signals) and for RGB I have R, G, B, Sync, L Audio, Right Audio (6 signals), so surely I can check if the sixth signal is active with a detector and then either trigger or not trigger a switch the reroutes the signals through the converter?

Does this make any sense? I tried googling for a switch that is toggled by a current but I didn't find what I'm looking for.

I know I am a total beginner and this is probably all idiotic, but can someone at least ballpark me into the right direction with this?