You should be able to manually turn the flywheel to get access to the bolts that hold the clutch on. Ideally, you should release each bolt a little at a time to prevent the pressure plate assembly from warping. The same goes for when you put the clutch back on. Tighten each bolt a little at a time.

I recommend removing the spark plugs to release some of the compression to make the flywheel easier to turn. Maybe even remove the head too. If you still can't turn the flywheel, something is definetly wrong! Either you are a 95-pound weakling wink wink or there is something binding up inside. Drop the oil pan and check it out. Maybe you need to employ that spare gorilla I was talking about! :p

Good Luck my friend, you WILL succeed!

Steve
Stovebolt Gallery page for my truck