2 monotwix
You must edit *.skins file.
lod = {"model name", 30};
lod = {"Lod1 name", 500};
lod = {"Lod2 name", 1000000};
collision = "name-COLLISION";
Su-25T skins for example
lod = {"SU-25T", 30};
lod = {"SU-25T_LOD1", 500};
lod = {"SU-25T_LOD", 1000000};
collision = "SU-25T-COLLISION";