[gnea/grbl-Mega Issue#24] Possibility to redefine home location

Hi, I’m using grbl mega with bcnc. I have limit switches installed and have home in back-right-top corner so it’s sort of in compliance with “all-negative workspace”. When arduino is just loaded and connected, it reports machine coordinates as 0,0,0. After home cycle the coordinates become -1,-1,-1. Is it possible to change these values to 0,0,0 or better 1,1,1?
bcnc guys told me it’s a grbl thing but I could not find it myself so far.