Hi Roto31,
When rigging the switch as in the sawtooth switch thread, for each of the switches, (S1, S2, S3 - power, reset, programming) the result is a simple short between switch + terminal and the ground track on the switch board as that is how the Mac board worked. For the LED it is similar, there is a LED + connection and that is actually connected to the Anode via an onboard 40 Ohm resistance (which does not affect its ability to light fine on my board) and the common cathode connection for that two colour LED is connected to the board ground. There is only one ground connection on the ribbon cable and assuming that on the board you are using all switch negative (-) connections (and the LED - connections) are internally connected to ground on the motherboard end then as long as there is a single ground connection linking the switch board to the mobo all functions should work correctly.
On my conversion I hooked up the power switch + and the common board - (ground) to the power switch + and - terminals respectively on my mobo (which is GA-P55M-UD4) and the LED + connection to the power LED + connection (leaving the LED - connection open/not connected) and the LED and Power switch functions work fine. Holding the power button pushed while the machine is running should have the same effect as holding a regular power switch pressed - i.e. if a normal PC momentary switch produces hard shutdown then doing that with the modded Mac switch will do the same - in the end it is just a regular momentary switch.
I have not hooked up the reset + or the programming switch +, but if my assumption that the mobo uses a "switch to ground" connection is correct then there is no reason why hooking those up would not work. You can verify if the mobo works that way by just doing a simple multimeter test (with power disconnected from the machine) to check if there is zero resistance between reset switch - connection and ground. If there is, then the mod will work, if there is not, then it won't......and in that case then it is better instead to do a full hot wire and to cut traces on the switch board to remove all of the common grounding between the switch connections. I'll do a multimeter check later on my boards just to verify what the status is of the negative sides of the various connections to see if they are indeed all connected to a common ground level.
