I patched an executable for a DOS game that I'd extracted from a game.gog image but don't know how to create a new image the DOSBOX will accept.

game.gog is just a normal .iso file.
Any software that can make ISO9660 image will do it.

I keep trying that but GOG's DOSBOX wrapper won't accept it for some reason, It just keeps crashing whenever I try to boot it up with the new game.gog.

I know this is posted years later, but in case anyone finds this down the line, I managed to build a game.gog image that the GOG dosbox config recognizes and launches the game from.

I got it to work by trying a the ISO making program: http://www.winiso.com/products/winiso-free.html

Isn't it (at least sometimes) actually a .bin file? I'm sure I remember there being renamed bin/cue file pairs in some GOG DOSBOX based games.

Edit: Fell for the necro.