Muwum used some advanced LUA techniques for Battleglest. There is a Lua sandbox in Megaglest which blocks them, because these could be potentially dangerous concerning security. You need to disable the Lua sandbox in the Megaglest settings for Battleglest to work.
Sadly after doing so and creating the files version.txt and subversion.txt (in the main mg folder and with any content) Battleglest does still not work for me. But you may try. Maybe its just my lua version.
(We had problems back then, when i made some models for muwum)
I think this whole Project stopped, because megaglest is not made for such a conversion. Units in Megaglest do not react very fast and Muwum really used a lot of lua which caused further performance issues. It was just not fun to play like that. Maybe someone could improve that further or todays computers have better performance.