same question here, did you already find a solution?
perhaps you want to use a superboxselect.
Than this could be of help:
https://forums.modx.com/thread/79754/cmp-superboxselector#dis-post-443020
If you are looking for an easy way to create your CMP you can also have a look into MIGX and its MIGXdb - CMP - configurator.
There is it possible just to use a listbox-multiple inputTVtype for your table-fields
Sorry, nothing to add. We bypassed that part of the project, which wasn't essential, and may never come back to it.
Jason