I find it hard to believe that you couldn't get ahold of Tom at Candcnc. You might also try to catch him on his Yahoo group.
I don't work with Wincnc, but from what I understand, you have to remove their driver card from within your PC, and just install Mach3. It will be assigned a parallel port from the setup menu.
I want to say that you will just have to get another parallel port card, plug it in to the motherboard, and assign it in Mach as well.
I have been told by a number of people that it is a simplistic process, and quite worth it in the end.