They are not the same and you will not get the same functionality from both out of the box.
The trick is that most AC units these days are digital and everytime you turn it off (as the Johnson and Rancos are normally wired to do) you have to re-set the controls. The other issue is that window AC units are not designed to cool that low (36 for example). They can, you just probably can't set it to '36.' So you need to 'trick' it into cooling lower.
The "CoolBoot" bypasses all these problems by putting a wire over the AC temp probe and senses the temp coming out of the vent and the room. Probably uses some PID control to set the room temp. So, if the room temp is right, it tells the AC it is at the right temp., if not, it tells it to keep running. (I am essentially deducing all this from the 'coolbot' website.)
If you want to use a Johnson or a Ranco, you are going to have to figure out how to keep the AC on all the time and essentially apply the control to the AC's on/off system internal to the AC. This can be tough if you are not electrically inclined. I am sure there are some guides on the web, but every AC is different.
EDIT: If it works as well as claimed the CoolBot would be indeed cool, but there is no way I would pay $300 for it.