I'm confused...why did you compile with Icarus if you want to use Xilinx Power Estimator?
If you compile your Verilog design files in ISE then you can export a power estimation file of the as built design to the power estimator and get a very accurate power estimate for the target Xilinx device.
If you are trying to get an estimate for something other than a Xilinx part then you don't want to use Xilinx Power Estimator as the results won't be applicable.