How to use:
Open assembly (if you havent downloaded it yet check the link named assembly)
Goto TOOLS - Map Patcher - Apply Patch
Put Driveable dumpster.asmp as the patch and the forge_halo.map in as unmodifide map.
name your modded map file and then replace you forge_halo.map with the new one you created. (Remember to always save a backup of your maps!)