The other way around was explained by Captain Sim:


Captain Sim wrote on Oct 30^th, 2007 at 1:47pm:

In order to merge the A model textures into the D model: - Copy desired texture.X (X=texture name or number) folder from the FA-18 to the CS_FA-18D airplane forder. - Copy texture.cfg file from any D texture to the new texture.X folder (overwrite existing texture.cfg) - Copy from the A aircraft.cfg to the D aircraft.cfg corresponding  [fltsim.XX] section. Make sure the new section has unique names and IDs and model=d texture=X

basically, it's just the same.
hope it helps...

Tyrion