what you describe here is correct, but do not forget to edit several .cfg files as well:
- sea\
NKMCS_Heito\NKMCS_Heito.cfg:
save to sea\
NKMCS_HeitoX\NKMCS_HeitoX.cfg and change the following lines (edit using notepad):
ClassName=
KMCSHeito to ClassName=
KMCSHeitoX (or whatever you want to call it)
3DModelFileName=data/Sea/
NKMCS_Heito/NKMCS_Heito to 3DModelFileName=data/Sea/
NKMCS_HeitoX/NKMCS_HeitoX (path to the NKMCS_HeitoX.dat file without the .dat extension.
-Roster\Japan\Sea\
KMCSHeito.cfg:
save to Roster\Japan\Sea\
KMCSHeitoX.cfg (or any filename you want) and change the following lines (edit using notepad):
ClassName=
KMCSHeito to ClassName=
KMCSHeitoX - must be the same as the classname in sea\NKMCS_Heito\NKMCS_Heito.cfg
and change all the TextureName= entries to the new filepaths, so for example change TextureName=data/Sea/
NKMCS_Heito/NKMCS_Heito_T01.tga into TextureName=data/Sea/
NKMCS_HeitoX/NKMCS_HeitoX_T01.tga
I hope this was of any help to you.
If you need more info you can read this excellent and very extensive tutorial by mikhayl:
http://www.subsim.com/radioroom/showthread.php?t=134575
It was written for playable units but for non-playable units it works the same only without .upc files.