The B model is just a colour change according to the manuals, the website and the spec sheets, so it should work on it just fine also. If you are worried you can obtain a 2nd hand A model from Trio here
. This is why I bothered to try to enable these features because I got the cheaper meter and the price difference wasn't just $20-30 for me, it was over $100.
The process was pretty simple, I did a tear down to inspect it and comment on its build on this forum. I noted that others had upgraded the firmware in other Agilent devices to fix firmware bugs, so I kept an eye out for an EEPROM when I had it apart. There was only one there, so as a quick and simple test, I shorted out the i2c lines to prevent the micro talking to it on start up, which presented an error, but was still functional. Checking the setup menu I found I had the additional options to configure, and all the other values were set to FF or FFFF, etc.. so the micro defaults values to FFFF when it cant read the EEPROM.
I then programmed a STM32 development board to dump & flash the EEPROM and had a look around in it. The data is pretty easy to see how it is segmented, calibration data, then device name, model and serial number, and after that the config space.
Since I knew that 0xFF was a good value to set to enable these features I started out by setting portions of the data to all 0xFF, powering on the meter and checking if it had the additional features. If it didn't work, I reversed it, and tried another area, until it did work. Then I just repeated the process until I found the exact byte to change, and experimented with it's value.
A word of caution if you attempt this in any meter, make your EEPROM read only by pulling the write protect pin high before you start to be 100% sure you back up its contents before altering them, as the EEPROM also contains all the calibration data for your meter, and changing it will cause your meter to read things incorrectly.