Jon, I think he's talking about his router, with his own custom fixed tooling.

Jeff, from the TurboCNC manual.
A means of setting tool offsets is provided under this menu item.
Before any of the tooling offsets can be set, a reference location to zero must be set. Once the reference is set to a zero location, all other tools are to be moved to this location. You may use either a tool as the reference, or may make a special tool setting gauge. Once the reference location has been set, load the actual tools and move them to the reference location, using the jogging controls. TurboCNC will then record the offset locations for each axis.
I haven't used it, but from what Jon's saying, I don't think you need the G43. You setup the offsets for each tool, relative to either a single tool or a reference value. Then, when you do an M6 and call the tool, the offsets are automatically applied. Our commercial machine at work works sorta like that. Set up all the tool lengths, and then whatever tool your using, the machine knows how long it is, so, for instance if you move to Z-1.35, no matter what tool you're using, it will always move to that depth. Hopefully I'm right here. Jon?