The carrier cab contains only the programming code and the 1X username and password.
What happens is when a first time connection is made to evdo, the network verifies the settings in the M.IP Default Profile, these values generate the HDR password. Then the connection is successful.
During the rom flash, the M.IP Default settings are made generic with blank values in the carrier specific parts. The carrier cabs dont touch these at all i believe.
Theoretically, if you can connect to evdo, and you deleted the hdr password. then next time you attempt a data connection, youll still connect as the hdr password will be auto generated due to the correct values in M.IP Default Profile.
Naturally, youd be crazy to test it out without writing the password down