Well, that was what we did back in days of hex editing. What you want to acomplish with this?
Also, mission.lvl is for all shipped levels, so in multiplayer enviroment everybody have to have same mission.lvl.
If you want to mod official levels, you can see some old stuff we did at gametoast.com (mini-mods section/downloads) but make sure you back up your original mission.lvl and level you are replacing....
GT-1 team at: