yes you must use MTP mode. However I had lots of problems getting this to work (and still have an issue - more on this in a moment)...key to this working at all is, if you are using Windows XP, (Like i am) I had to install Windows Media player 11 (or whatever the latest is may still work, 11 was the latest ver when I tried) even if you are not going to use it.
I guess it loads drivers you need. Until I had done that, NOTHING worked.
Now my current limitation is that once I've synced, I can take my clip and rate my songs = all good.
I then connect back the clip to my PC and ratings and play counts transfer over = still all good
then I sync (with J River setting it to remove those tracks not in playlist - I set up smartlists to only keep UNRATED songs on my clip) = PROBLEM, it says its syncing but when you remove Clip there is no music on the clip at all.
Only solution is after connecting the Clip and getting the ratings etc across to the PC, is to disconnect and Format the clip (from the Clip Menu), then set it back to MTP mode and sync from scratch...
If anyone has a solution for this or a better workaround, I'm all ears.