I'm the guy behind the project, and I'd like to thank cbsks for posting it. If anyone has questions, please feel free to hit me up on Twitter (@nwsayer) or post on the hackaday.io project page (https://hackaday.io/project/5880-crazy-clock)
That would necessitate changing the gearing ratio between the hands, which is beyond the scope of this project.
I'm assuming you need to unplug the battery to set the "true" time? Else you might be adjusting the "I'm in my +10 minutes phase" (for early clock, f.ex), turning it into late clock. (?)