You should have a selection named in all the resolution LODs
You need that selection defined in cfgModels like you would define zasleh
the first selection name is 0, the second 1 etc
class cfgModels
..... class myModel: All
{
selections={1st group, 2nd group};
};
then setojecttexture[0,"filename"] would change the texture that is applied to 1st group.