OK I've got it - we were sent a couple of pre-production samples and we had no instructions but I've figured out how to do it!
It's possible to both add to playlists and play the tracks on these playlists randomly.
While a song is playing, go back to the filelist using the Fn/Music button and go into 'folder' which should highlight the current song.
With that song highlighted, press the centre button and hold it down for a second - a menu will appear with 'add to list 1, add to list 2, add to list 3'. Select the list you want to add the song to and press the centre button again - it will be added to the bottom of the list.
Then to play randomly (works like 'shuffle' as songs are not repeated until all songs in the list are played), go to settings/play settings/repeat mode and select random.
To remove songs from the playlist or move them up and down in the list, just highlight the song in the playlist and hold down the centre button for a menu.
And we're still taking pre-orders
http://www.hifiheadphones.co.uk/lotoo-paw-5000-portable-lossless-digital-audio-player.html