You always could plug in the TPS and Map sensors only without the VSS. Since the VSS is a hall effect switch (logic levels of 0 & 5 volts only) the engine will idle fine with out the VSS installed. The bike won't ride well without a VSS signal but as long as your not moving, it should idle fine without a VSS.
This would give you an idea of how many problems your actually dealing with. (VSS sensor shorted, fuel regulator holder leaking, ECM reference supply pull up strength etc)
But like Glider suggested, a discolored terminal is a sign of a poor connection so I think your on track w/ a good plan.