Lock Dizzy for injection/programed ignition

Hello peoples

I have a point to clarify, I have an Essex V6 that I wish to use a MSD6AL-2 Programable on for ignition control. As the MSD will now control up too 32 load points, the stock factory vacuum and mechanical advance needs to be locked up. I assume that the dizzy should be locked in full advance mode and the ignition retards from that point to control ( is that correct?). The point to clarify for me is how does one lock the dizzy, so that if a problem occours, I can unlock it and return it to standard?