i don't think the micra would have a oil pressure gauge sender from factory (no oil pressure gauge on dash). You'll need to get a sandwhich plate for the oil filter to give you a sender input location.
Or you can put a Tpiece where the factory oilpres sensor is fitted (aprox just left to the oilfilter from memory) and mount your aftermarket oilpressure gauge sender for your gauge to the Tpiece you mount there.
Works great if you are only fitting the one extra gauge. If you are planing on fitting more than one sensor etc go for the sandwichplate solution. But as 33driver asks above you will need a dedicated sender for the gauge..
Here you go, sorry about the delay!
In this picture you can se that a Tpiece is mounted in the location where the factory oilpressure sensor was fitted and now the oilpressure for the turbo is taken from..