I have been procrastinating in doing this since it was released. (Method 3). I wanted to get it done while the weather is warm since I do not have a garage, but it is so easy to forget about it because I don't need the heat right now.
I finally got around to doing it, plus some extra stuff since I booked the day off work.
I first did this with a nice circuit board, but it didn't work as advertised, after some trial and error and re-reading, I found that R3/R4 were dropping the voltage too low, so I got rid of them, and now it works ^_^
Also, I used a 2N7000 mosftet, I think there is a typo, 1N7000 indicates a diode, not a transistor.
Because I had to do trouble shooting, i found it was easier to solder point-to-point, though I worry about the durability of this circuit. I have a layer of kapton tape between my components and the board and over the components to hold them down. This tape is safe for electronics and works in high temperatures.
Here are some pictures of my insulation mod. I initially used the same cheap pipe-insulation that is common, but I didn't really like it, plus the R value (insulation ability) is better on this metallic bubble wrap. According to the lowes website, this stuff is R4, vs the foam pipe insulation which is only 2.4
I have a sticky foam tape with foil on my reservoir, I just found it in the store, I don't have a link for you. (I bought my materials from a local Rona hardware store that is having a closing/moving sale)
I wish I could have gotten to the PTC heater itself, but I didn't have the tools (or the time) to get my tire off and the car lifted, so I went in from above instead. It looks nice, but I think I could have done better.
Here are the photos. any un-wrapped pipes you see are part of the coolant loop, so we do not want them insulated. (link goes to skydrive with more photos)