And I assume you'd want the signal return (this will be the wire which shows 1 volt at idle and 4 volts and change at WOT. When it achieves some given voltage, your kit will recognize it as WOT and enable the nitrous.
Does your kit recognize a 5 volt RREF? If it doesnt, the voltage from the TPS sig return might not be calibrated for the nitrous switch.
Good luck.