I would call the companies listed in the yellow pages and see what they have to offer.

They are not hard to do, just a nightmare of piano hinge fitting.

brickeye, why would you use piano hinge? I've seen a few of these but never paid much attention to them. They always seem to be hanging loose and blowing in the wind. Maybe piano hinge would have been the answer.

The secions of the door are piano hinged together in line with the door joints.
I use regular hinges for the actual hanging hardware.
I make the doors so the panels are the same size as the garage door panels and there is enough material to attach the hinges.
There used to be someone making doors with access openings already in them, but I have not checked on that in about 10 years.

Most all Garage Door manf. do make a door-in-a-door garage door. The added expense stops most lookers though. The last time I priced one for a customer, the added cost to the door to me, (a dealer) was $850.00 added over the cost for the door itself. And the door must be the top of the line heavy duty model. Those are the only ones that the manfactures will modify for structural reasons. So the door you must buy is usually expensive to start off. Then the added cost of this "option". The $850 is the dealers cost, we will usually add a mark-up to this price as well.