Sorry. T0 automate the install of firmware you need to use fw_update and you need to use a full /path/to/the/file. Example using a "dot" to indicate a full path beginning with the current directory (untested, just typed...):
Code:
$ ftp http://firmware.openbsd.org/firmware/5.5/radeondrm-firmware-20131002p0.tgz
$ sudo fw_update ./radeondrm-firmware-20131002p0.tgz