The reason that will never work in any OS (except linux, perhaps) is because the disk will have a Mac partitionmap and Mac HD drivers on it. So plug it into a PC and Tada! ... nothing.
Conversely, you could do the partitioning on a Pc and the mac wouldn't be able to read it.
Its portable and many of my friends have PCs, and can't read it in Mac OS format. Unfortunatly in MS DOS format, the disk doesn't like certain characters, and I don't really want to change the names of 3000 mp3s.
If it is possible in Linux, like 1337_5L4Xx0R suggested it may, you could try to find a Linux application to do this with, and run it under X11... Just a shot in the dark.
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Conversely, you could do the partitioning on a Pc and the mac wouldn't be able to read it.
Your best bet is to reformat your friend's computer and install linux on it without asking them first.