Thanks for the suggestion. Though you have made a perfectly reasonable request, we (the developers of ICE) don't really work on image file formats -- we rely on the Windows Imaging Component (WIC) to read image files. It's an extensible system,
and therefore ICE will happily read a .FIT file if you can find or develop a WIC-compatible codec for the FITS file format. Please see this page for more information about the WIC codecs that ICE uses:
http://research.microsoft.com/en-us/um/redmond/projects/ice/codecs.htm
Sorry I don't have a more helpful answer!
Eric Stollnitz, Computational Photography Group, Microsoft Research