Assign drive letter to USB drive (XP)

Hello,

Is there a way to force ANY USB drive to use a particular
drive letter?
I can change the drive letter to P: in disk management
mgmt but this only works
if THE same USB drive is used.

If another one is used it appears as D:

I work in a school and must restrict access to some
drives (eg D so we would like any USB drives to always
use P:.

Any idea anyone???

Thanks
Aïsha