If you haven't already..Try undoing the bolts that hold the whole regulator mechanism to the door shell including the bolt for the motor (10mm socket).. then you may be able to lower the whole lot a bit including the actual window glass until the nut for the window clamp is revealed, it should show through a cutout in the door shell if you can lower it a little..then once the clamp is loose you should be able to wiggle the window glass out of the top of the door, inturn freeing up the regulator to be manouvered out of the lower part of the door.
I think this is what i did on one of my doors anyway.
On the rear regulators i believe it's only three 10mm bolts (2 for the runner, one for the motor) as there's only one runner compared to the front regulators two..also, one clamp on the rears, the fronts have two.
Hope that helps.