Have you tried this?
Code:
type hounds_of_culann
;--------------------------------------
skeleton fs_2handed_berserker
scale 1.1
indiv_range 40
texture britons, bi/data/models_unit/textures/BI_unit_hounds_of_culann_celts.tga
model_flexi bi/data/models_unit/BI_unit_hounds_of_culann_lod1.cas, 15
model_flexi bi/data/models_unit/BI_unit_hounds_of_culann_lod2.cas, 30
model_flexi bi/data/models_unit/BI_unit_hounds_of_culann_lod3.cas, 40
model_flexi bi/data/models_unit/BI_unit_hounds_of_culann_lod4.cas, max
;model_sprite 60.0, data/sprites/romans_julii_roman_peasant_sprite.spr
model_sprite britons, 60.0, bi/data/sprites/celts_hounds_of_culann_sprite.spr
model_tri 400, 0.5f, 0.5f, 0.5f
This is what I had to do to get it to work for me.