We use those long multi-outlet power bars (power strips?) with 6 or 8 outlets. As long as the flexwatt is all the same type and the total wattage isn't excessive for the tstat, I've been told it's fine.

I did note on the instruction booklet with our Helix that it's recommended you use a power bar with no surge protector as the Helix has it's own fusing system and one can mess up the other.