Victory!
Many, many thanks, privateer.
Now I'm going to push my luck and see if I can have two POS_Helmet dat files in the same directory, one for the NCO cap and one for the sailor headdress.
I might have to make a directory structure like Body01 and Body02 to make it work, I suppose.
If anyone's interested, I'll upload the one file, though the operation's quite easy to do using Silent 3ditor (export 3D model from the OFF, import it to the POS).
Thanks again, privateer.