In all honesty, I would probably say get one of the cheap 5-axis BOBs off ebay.

They've got a relay output, and a 0-10V output, along with extra inputs and outputs.
You'll need to wire in a 12-24VDC for the 0-10V output to work, and IIRC you need to connect the USB (or the 5V to the relevant terminals) to power the optos.

Just search on eBay for "5 axis breakout", and you'll get plenty options.
And you'll also need a straight through parallel cable to go with it (at least I think it's a straight through that you need, I've never actually used a parallel port for CNC!)