I don't own the IC-R2500 (yet), but I do have the software for it. It appears the the ".mch" format is the native format for this radio. I went to the file editor, and selected open file. It found and loaded the ".mch" test file which I downloaded from the Icomreceivers.com with no problems.
OK, I figured it out, you need to use the "Memory Edit" button and not the "Clone" button, then "open" the saved .mch file. Once you have the frequencies in the software, you can "clone" them into the R2500. You will need to "convert" the file from the PC to the radio using the proper selections in the clone window.
*Whew*, not an easy way to do it, but it works I guess.