I just cut one
I made the mistake of leading my main halyard out the wrong exit sheave when preparing the mast this spring. ('89 H30G) It didn't run fair to the winch. Rather than motor to a marina and pay to have the mast lifted again, I cut a 2" D hole in the starboard side of the mast, using an ordinary hole saw, about 4" up from the bottom. This gave me access to the halyard sheaves and the wiring connections -- very convenient. For a deck stepped mast, there are no bending forces on that part of the mast, just compression, so I believe that this is safe. However, I recommend keeping any hole as small as possible. A 2" hole is large enought to work with. Cut at your own risk.