default minimap images were not disabled last time i checked, you just add this in the gmap file itself:
PHP Code:
MINIMAPIMG mapimg.png
as for generating an image the level screenshot method didnt seem to be as convenient as the nw2png project, but nw2png required filenamecache.txt which has not been used since v6. luckily i still have a copy of the v5 client which upon opening will re-generate filenamecache.txt