Yay! I worked it out! Study my command line.
I put the bitmap in the same dir. as the exe.
I'm proud of myself considering that I know nothing about command lines
Edit: I didn't work it out, no RGN file was created. :doh:
Edit 2: I did get it right! I did a search and found the rgn file in a different directory! The nice new region creator with the GUI is much simpler lol