1mb in size? I dont quite understand because the content of the BT2 disk is around 700 mb.
Well you could do it automatically by using this program:
www DOT forums.remote-exploit DOT org/showthread.php?p=27171#post27171
Or you could properly copy the BT2 files inside the iso to your usb.
Also, Check the MD5 of your iso to make sure it isnt corrupt.