This should now detect the right firmware version automatically. If the firmware is unsupported it will display an error and refuse to load the CFW.
Simply replace the file from the OP with this one, load brahma and the arm9payload as usual, and press START to load the CFW once you have verified that the detected firmware version looks correct. When enough people confirm it's working, I will make it autoboot the CFW by default so there is no need to press START.
If people have any problems with it detecting the wrong version, simply tell me the contents of the "FIRM: KERNEL:" line, which firmware it detects and which firmware you actually have and I'll have it fixed shortly. Unless there are errors in the list on 3dbrew that shouldn't be an issue though.