It's easy and safe enough to merely swap textures if you know what you're doing. I would recommend "commenting out" the original line(s) with a ; in the beginning though, so that the changes are easy to reverse if necessary for some reason. Eg. what it looks like if you switch the Gallic factional textures:
Code:
type celtic_cavalry_leuceepos_equitesgallovrum
skeleton fs_hc_javelinman_big, fs_hc_spearman_big
indiv_range 40
;texture gauls, eb/data/models_unit/textures/celtic/ebceltic_cavalry_leuce_epos_psycho_gauls.tga
;texture scythia, eb/data/models_unit/textures/celtic/ebceltic_cavalry_leuce_epos_psycho_scythia.tga
texture gauls, eb/data/models_unit/textures/celtic/ebceltic_cavalry_leuce_epos_psycho_scythia.tga
texture scythia, eb/data/models_unit/textures/celtic/ebceltic_cavalry_leuce_epos_psycho_gauls.tga
...
...and backing up the whole file is of course recommended on general principles.
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