I think that's a great idea. I've actually tried to talk contractors into doing that for me but they shy away. That might be because I'm pretty advanced in my skills and want help with pretty large things like setting forms for and pouring a foundation for an entire house. In most of the cases where I would need help I would basically be paying to be a short-term apprentice. Which would be worth it to me though not if it cost more than just having someone else do the whole thing.
Basically, it would be ideal to have the contractor come in, tell me where to set the forms and how to prep the site (backfill, tamping, etc) check my work and then lead the pour with me mucking (and learning).
I currently have this type of relationship with an electrician who is a friend of a friend. I pulled a couple runs throuht my basement, drilled all the wholes in the joists, ran the wire, put in a junction box etc. He came and inspected my work and connected it to the panel.
That is the type of stuff I would consider paying for. However, I can and will do a lot of research on the internet to get at the "what should I do" aspects of my various DIY'er projects.
I would have paid a consultant to tell me what to do and how to do it when I jacked my house, but they all wanted to do the whole job, understandably, so I did it myself.
Off topic: A lot of DIY'ers get quotes and ask a lot of questions only to end up stealing the advice for free and doing the work themselves. Those would be the types you'd be working with....