Put the cdr into the burner:
Type: cdrecord -scanbus
Note the device numbers of the cdrw because you need to use that information in the next command (Mine are 0,0,0 )
Type: cdrecord -v -speed=4 -dev=0,0,0 filepathname.iso
Note: You might have to run the scanbus command as root so type: su
And enter your root password.
End of story! ISO ready.