I understood what you need, but giving you another solution (mb those old numbers which are going to be replaced are used on other skins, then those skins will also have swapped numbers)
Su-25T got new LOM format with Su-25T.skins file, where all textures used by skin can be replaced.
just replace in "material = {"numbers", "standart", "rus-code-numbers-ver1-B-w-W.TGA"};"
"rus-code-numbers-ver1-B-w-W.TGA" with new file name "numbers-white.tga" for example
where "value = 0.1" has to be skin slot number/10