There are no holes in the frame, but the post-64 guns have the screw heads on the outside. I wonder why it only took them 70 years to think of that!
Oldandslow, for the old guns, if the guides have to be removed, the only way is to do what just what you did. And yes, it is tedious and a real PITA.
If doing more than one, you can rig up one of those small ratchet wrenches and modify a power screwdriver bit. But Hawg is right; unless they have to be changed or repaired, there is no need to take them out. They can stay in for any other purpose, including tank bluing.