I forget this every time I reinstall my machine, so I think it's time to document it somewhere.
Unzip it and double click on the colour scheme you want (light or dark)
Open iTerm2's preferences.
Go to colours, load presets and select Solarized. Make sure that the minimum contrast slider is set to low
Click on text, make sure that "Draw bold text in bright colours" is disabled
Done! You should now have a working colour scheme