As a user of this method myself, I whole-heartedly agree with the esteemed Brian H. Leave the thermostat in. I use X10 on all aspects of my HVAC (baseboard emergency heat, my hydronic system, and my fan forced fuel oil furnace. I also have VERY reliable x10 signal propagation in the house. Twice in the last two years, I have awoken to a cold house, and once I can home to a very hot house.
I'm currently working on a series of hardwired over-rides to prevent this.
BTW, It was a stuck button on my Sears controller jamming the signal every time.