The "How-To" is actually very easy. It takes about half an hour if you are mechanically inclined and have taken a dash apart before. It doesn't require any soldering, just scraping.
It's so annoying having the compressor come on in the winter when you actually don't need it. The heated air will be hot enough to clear your windows. Plus, your gas mileage is taking a hit when this happens.
Do the "How-To", you won't regret it. Plus, you get FULL control over your HVAC system instead of Mazda dictating it.