You should be able to create an m3u playlist on most popular media players (Windows Media Player, MediaMonkey, iTunes, WinAmp, etc.), export it, and copy it over to your BB in mass storage mode.
The BB media player will recognize it from anywhere on the media card - whether the BB media player correctly lists the contents depends on the m3u format and the location of the m3u relative to the files it references. I edit the m3u to the format shown below (aided by Media Monkey) and copy it to the root of the music folder (\Blackberry\music). Below is an example of the contents of an m3u that would work for music located in the "\Blackberry\music\Green Day\American Idoit" folder.
.\Green Day\American Idoit\American Idoit.mp3
.\Green Day\American Idoit\Jesus Of Suburbia.mp3
.\Green Day\American Idoit\Holiday.mp3
.\Green Day\American Idoit\Boulevard Of Broken Dreams.mp3
.\Green Day\American Idoit\Are We the Waiting.mp3
.\Green Day\American Idoit\St. Jimmy.mp3
.\Green Day\American Idoit\Give Me Novacaine.mp3
.\Green Day\American Idoit\She's a Rebel.mp3
.\Green Day\American Idoit\Extraordinary Girl.mp3
.\Green Day\American Idoit\Letterbomb.mp3
.\Green Day\American Idoit\Wake Me Up When September Ends.mp3
.\Green Day\American Idoit\Homecoming.mp3
.\Green Day\American Idoit\Whatsername.mp3
Notice the ".\Artist\Album\filename" path resolution to guide the media player to the file location. The preceding "." before the folder\file path is important as it indicates the parent folder to the media player, where the m3u file is located, in this case "\Blackberry\music".
You could also use actual unedited m3u files directly (example below). When using this format, you have to place the m3u file in the same folder as the mp3 files referenced (in this case "\Blackberry\music\Green Day\American Idoit"), otherwise the media player won't be able to locate the mp3s and the playlist will indicate "no files" in the media player.
#EXTM3U
#EXTINF:174,Green Day - American Idoit
01 - American Idoitmp3
#EXTINF:548,Green Day - Jesus Of Suburbia
02 - Jesus Of Suburbia.mp3
#EXTINF:232,Green Day - Holiday
03 - Holiday.mp3
#EXTINF:260,Green Day - Boulevard Of Broken Dreams
04 - Boulevard Of Broken Dreams.mp3
#EXTINF:162,Green Day - Are We the Waiting
05 - Are We the Waiting.mp3
#EXTINF:175,Green Day - St. Jimmy
06 - St. Jimmy.mp3
#EXTINF:205,Green Day - Give Me Novacaine
07 - Give Me Novacaine.mp3
#EXTINF:120,Green Day - She's a Rebel
08 - She's a Rebel.mp3
#EXTINF:213,Green Day - Extraordinary Girl
09 - Extraordinary Girl.mp3
#EXTINF:246,Green Day - Letterbomb
10 - Letterbomb.mp3
#EXTINF:285,Green Day - Wake Me Up When September Ends
11 - Wake Me Up When September Ends.mp3
#EXTINF:558,Green Day - Homecoming
12 - Homecoming.mp3
#EXTINF:252,Green Day - Whatsername
13 - Whatsername.mp3
You can name the playlists whatever you like. For what it's worth, I use a standard naming convention of "Artist - Album", or something like "Artist - Favs" for a favorites mix.
This may be somewhat confusing...good luck!
Oh, and I had to intentionally misspell the word "Idoit" because the CB forum was replacing it with asterisks....