Rudolph,
The best place to start looking for a mechanic who will let you assist with the annual is to start asking other aircraft owners on your field. Be a bit of a ramp rat, strike up conversations and see where it leads.
The other thing is to find the more "one horse" type of operation on a nearby field. Then you develop a relationship that works into trust, then they will open the tool box for you.
My AP/IA was hesitant about letting me work with him on my plane, but I prodded him a bit and he finally started me with some easy tasks (I had already been working on a prior airplane before moving). This grew to where sometimes he calls me up to take time off of work to come and help him (i.e. removing my engine and tearing it down for a new cam). Sometimes I have to remind him that I need to stay employed to pay his bills.
Just ask around and hopefully a club member from your area will have some advice too.
