If you look at page 20 of my roto damper thread I posted a diagram showing suggested wiring for the CAT5 jack (including probes) for the new HM models as well as the older ones. The choice of how you use the spare wires in the CAT5 jack are somewhat subjective, so this is not in stone, it's just a suggested way to go about it.
Keep in mind, however you decide to use the spare CAT5 wires, there are no traces on any HM board to bring the probe leads over to the CAT5 jack, you are going to have to add jumper wires from your probe jacks over to the CAT5 jack before it will work. I suggest that you connect them in a similar manner as the optional ambient temperature thermistor, on the third leg of the onboard probe jacks. This way the probes coming in via CAT5 jack will work by default, but if you plug a probe directly into the HM that probe will function instead of the probe coming in on the CAT5 jack (for that single probe).
