This is a start for the software: click here
Jut a word of caution; With all GPS systems operating without correction (or on the P-Signal :) ) the actual accuracy will not be especially good. It'll be ok if no two energy meters are within, say, 10 meters of each other. If they are any closer than that then GPS alone is unlikely to be sufficent to locate a specific meter.
The upshot? If a company advertises that their GPS is accurate to '2 meters', ignore the claim. The only valid accuracy statement is if they also declare the Cicle Error Probable (CEP) with the distance accuracy.