I could install your mentioned MUGEN KOFXII lifebar without any problem:
All I did were (I use MUGEN1.0):
1. put the folder KOF_XII in my mugen\data\
2. update the KOF_XII\fight.def with the MUGEN1.0 version by Kohaku (1.0 Patch)
3. change the line in my mugen\data\mugen1\system.def:
;fight = fight.def ;Fight definition filename
fight = KOF_XII/fight.def
** by default, in mugen\data\mugen.cfg, "motif = data/mugen1/system.def" is set up **