Sure, but listing is one thing and uploading another.
Are you saying you have managed to upload a RAW file ?
I just did the following:
rename CRW_1234.CRW to XXX_1234.CRW (using memory card reader)
put card back in camera
copy XXX_1234.CRW using the standard windows XP camera interface.
FWIW, files that don't follow the PFX_NNNN.EXT format don't seem to be listed.
Which camera does he have, and which prefix/extension is he using ?
Is he restarting the cam before plugging in USB ?
correction the steps above only worked when the corresponding jpeg does not exist. If the jpeg exists, the other file is hidden. However, when a known prefix is used (CRW_NNNN.CRW) the present, then both are shown and can by copied.