This has been discussed at the Z133 meetings.
The consensus is that in order to comply a climber would put on their tree climbing harness then the fall arrest harness over the top along with the lanyard. Then, when you get into position to work in the tree, set your rope/climbing system in the tree. Tie into your tree harness, test the setup and take the tension out of the line. Then, and only then, take off the fall arrest system.
As you move up out of the bucket you must take out the slack in your system and get into the tree.
This is not meant to be an 'approved' system. that would depend on too many variables, especially the rules setup by your employer.
Stay posted, someone may be able to site chapter and verse.