Once you are in Dothalo you can pretty much change everything you want, just make sure once you change everything in one item, say that sniper rifle, you click save changes, then when you are done with the map and want to save it, click fix encryption. When you open the map, find the tag you want in tags, like the sniper rifle, and then move the hex editor over from the left side of the screen and click tag editor at the top of it.
Note: make sure there is always a value in the boxes, even 0 or you will have to reset it by clicking 0 three times in the projectile or clip box.
Once you have dothalo just look up tutorials on how to use it, it's really quite simple really.
The favourites of mine are super strong guns, flying warthog, super jump, etc. I will check back here if you need anymore help.
