Using OmniRig, I can dial my radio to any frequency and VarAC follows. From there, using QSY or selecting a slot, marks whatever I had dialed as the CF and moves off the appropriate amount for the selected slot. Clicking the CF return button returns to the originally dialed frequency. Just what I would expect
I've had reports of that not working when using the internal VarAC CAT capability. It seems like VarAC does not want to leave the standard calling frequencies. This has been reported across several different manufacturers of radios.