Posted November 30th 2016
sudo apt-get install i2c-tools sudo modprobe i2c-dev ddccontrol dev:/dev/i2c-7 -r 0x10 -w 15
'i2cdetect -l' is useful for finding if there is an I2C adaptor. The register number, 0x10, can be read out by running 'ddccontrol' without arguments.
Addendum: to make the above work without 'sudo' and without having the manually load a module:
sudo adduser <username> i2c
sudo /bin/sh -c 'echo i2c-dev >> /etc/modules'