To update the driver pack, modify DPMS.ISO and replace "D" and all subfolders with the new ones. Then rename to DriverPack_MassStorage_wnt5_x86-32.ini to DriverPack.ini and replace the existing one.
To obtain the latest BTS mass storage driver pack visit:
http://www.driverpacks.net/driverpacks/windows/xp/x86/mass-storage/