Lets say you have all your mp3’s in /musik/mp3/ (all end with MP3). There are subdirectories in this directory and everything and you want to make a playlist of all of them and place it in /boot/ home/Desktop/playlists/.
There is already another playlist which you made directly with Soundplay (or CL-Amp) in that directory which is named sample. But in /musik/mp3/ there are a lot of mp3’s and you really don’t want to add them all by hand.
Then you just have to open a Terminal and type cd Desktop/playlists and
then:

find /musik/mp3/ -name *MP3 -print > allmp3s
copyattr sample allmp3s

There you go. You will have a working playlist of all the mp3’s in the directory. Be sure and use the full absolute path to your MP3 directory, or you may end up with relative paths in your playlists (which won’t work).
You could also do the find differently and only put the files that have jazz in their name in a playlist. So if you named all your jazz files jazz_someone.MP3 then you would use:

find /musik/mp3/ -name jazz*MP3 -print > jazz

copyattr allmp3s jazz

You can of course also change the directory and only put the files from /musik/mp3/rock in the playlist by typing:

find /musik/mp3/rock/ -name *MP3 -print > rock
copyattr allmp3s rock

I think you got the general idea. Just make sure that you made one playlist with Soundplay so you get the attributes right with copyattr and remember that the searches are case sensitive.