It's easy if you have a second parallel port in your PC or if you use a smoothstepper.
If you have (or can add ) a second port, just buy a second breakout board (like a C10) and this will give you all the inputs you'll need. If you have a smoothstepper, it will give you the equivalent of 3 parallel ports. Just add the C10 to one of them.
I would recommend using the ethernet smoothstepper and the C10 (or another BOB).
Willy