Ask HN: Business/initial-idea guy seeks technical founder; what's the process?

A non tech friend of mine spoke to me about his idea for a startup, and he needs help with the technical side of things. He's never run a business and has no technical experience. His idea has legs in principle but needs a lot of development (both from a business plan and technical perspective). I have great technical contacts plus I can help guide the process of building his idea up. If I was so inclined we could take his idea and build it out without him. I'm not that way inclined at all and want to make sure he's a part of the process, but I'm not sure how much value he will bring outside of the initial idea. I'm hesitant to just open up my contacts up without knowing how to best play this out; in everybody's interest.

What should I do?

Edit: This leads to another question- what's the best way to lay the right legal foundations to a founder relationship?