I switched Freddie to F/T without a hitch by thawing the mouse in hot water for about 15 minutes, drying it thoroughly with a blow dryer (and making a point to heat the head), then lying it under a heat lamp for extra overall warmth. I did the "zombie dance" thing for quite a while (upwards of 25 minutes) and then dropped the mouse for a break. That's when he ate; didn't even strike or coil, just started to swallow.

Good luck!