Not sure what you are asking, Paul. The two are unrelated. This plugin cannot be connected to User Custom Fields at present, and I don’t think it will be on the roadmap at present.
It might be worth asking nicely for it to be a feature though as it is quite similar in many ways and I can imagine it playing nicely with the Boolean UI.
On the other side, the functionality already exists in core (albeit currently a bit broken for multiselect fields).