Tweaking Max Block Length and Block Length Interval

To adjust the maximum block time and interval on the sliders, just open Terminal.app in Applications —> Utilities, then enter the following two commands (press enter after each line):

defaults write org.eyebeam.SelfControl MaxBlockLength -int [maximum block length in minutes]
defaults write org.eyebeam.SelfControl BlockLengthInterval -int [block length interval in minutes]

So, for example, to change it to a month-long maximum block with intervals at each day, you could use:

defaults write org.eyebeam.SelfControl MaxBlockLength -int 43829
defaults write org.eyebeam.SelfControl BlockLengthInterval -int 1440