I have recently bought a Peavey Ultra Plus. I am happy with my purchase, but unfortunately this amp does not switch between its three channels without a footswitch and I bought it without it (I'm stupid). Anyway, switch doctor is too expensive for my purpose ($80 is basically 1/3 the cost of the amp). I have no experience build pedals, but I know its a 7 din pin cable connection and the amp is compatible with XXX and JSX model footswitches. What do I need to know to start and finish this project?

I attached the schematic here. Thanks.