Make a folder named "ICE" and copy the XML and BMPs into this folder.
Move the folder into your Microsoft Flight Simulator X SDK\SDK\SimObject Creation Kit\Cabdir SDK directory and move it on top of the cabdir.exe so that a ICE.cab file will be created.
Move the new cab file into your main gauges folder.
Then you can add the gauge to your panel - i made the registration label smaller and i placed the gauge aside (2D and VC).
EDIT: from my C172 panel.cfg:
[Window00]
gauge45=n_number_plaque!n_number_plaque, 210,387,48,19
...
gauge48=ICE!IceWarning, 258,387,29,18
[Vcockpit01]
gauge19=n_number_plaque!n_number_plaque, 188,469,68,20
...
gauge22=ICE!IceWarning, 255,470,29,18
But reading the txt is the more important part.