Hello shepard, I'm in the process of trying to reinstate the IH mill wiring setup right now. I had it on the combo board and found it to be too noisy for my system to stay on line, so with that said I will recomend to get yourself a "SIIG cyberparallel pci card part no. jj-p00112-s5 " and go from there. Or you can try your breakout's connections and hope for the best. either way you will need some switching diodes #1n4004 and some resistors. Any time two limits are put on one circuit you need to isolate them with a diode. On the IH site there are some schematics available with several options and I am using the option where home sides are independant and limits sides are tied together through the diodes. I'll try to get together some more specific info and you can tell us more about what you have on hand there which may effect this wiring, such as do you get pc voltage feed thru you port that will need to be drawn down by resistors to make this work. the biggest resistor i have used so far is a 1k .5 watt on the e-stop circuit and i don't recall what for the limits and they may not be needed anyway. till later dude & your right it is not plug and play, I wish someone gave me all the right answers it would have been a lot easier ..... till next time.
Don
IH v-3 early model owner