If I understand, you are asking, if you can create folders on your media card?
Sure, Media / Explore is your built in file manager.
actually, i think he means the exact opposite.... when you put yer memory card in...the blackberry automatically creates a folder labeled "blackberry" which is where your Music, Ringones, Pics, and Video folders are created.....
i'm not sure if you turn off media card support if that will achieve what you are looking for.....
my question is..... "Why don't you want it to create this folder?"