I use Musicbee to my iPhone4:
In MB, Send To Playlist.
I use MB to copy the playlist files to another folder, and use MB to export a playlist .m3u to that folder.
I use 3utools to import that folder and sync it to the iPhone.
Its a long winded way around but here's hoping someone more knowledgeable than me could write a plug in for MB to directly access an IOS device, there are many iPhone transfer programs that do it.
If there was an iPhone transfer sync app that could import a playlist file and grab the music files from their original location to save the copying........