getting Low Oil Pressure signal.

Now (over)filled on oil, still getting Low P indicator.

presuming I do this myself, where is the Oil Pressure Switch located?

First cropped up a couple days ago, and yeah, it was way low on oil. Looks like i've also got a leak at at least VVT seal, maybe plug seal (COP itself?) and/or cam cover seal. It'll need all of them anyway.

Now (over)filled on oil, still getting Low P indicator.

The sensor is located on the oil filter mount. If you were low on oil and getting a low pressure indication, I hope you didn't run the engine before adding more oil. You should avoid overfilling by more than one qt.