Any program. I would say use Entity, but that's just my preference.
Also, why would you need the map signatures, if that's what you mean by sigs? I hope you're not tdata modding.
No, you wouldn't need the original signatures, unless your tdata modding, which like I've said in another thread already today, HaloMods frowns upon it. Just click resign in Entity and add it to your mainmenu and you're fine.