Unsinkable 2: Klemheist Mast Climbing System
I use this system when climbing without a winch-grinder. It is cumbersome and slow, but extremely safe. Basically it is similar to a one-line climbing system like a top climber... However your static line is the mast.
You can even hook a halyard up to yourself for extra safety.
I realize that this isn't viable for doing a ton of work aloft, but it could work in a pinch (like the OP's situation.)