Can I partition an iPod (nano, classic, shuffle) for use as a flash drive?
It can be done, but truthfully i would just spend the $15 on an 8gb USB drive. 

Anyway, one way of doing it:


Reboot ipod by pressing menu and center button for 5 secs.
Before apple logo appears (ie: do it fast) press play/pause and center for 2 secs
a green checkmark should appear on the screen. It is now in flash disk mode. Connect it to the mac 
Go to disk utility and format it for Fat-32 (or ntfs) 
Use it to install windows.
after you are done, start up itunes and Restore it. 


OBVIOUSLY you will lose everything in the ipod. So after restore copy all the music back.

You might be able to skip the first 3 steps and format it straight away, depending on your h/w version it might work, so check that first.