Yep, very simple. The mic calibration files are text files (even though they have a .cal extension), and consist of a list indicating frequency, response, phase. The phase is not needed. There should be a space between the frequency and response entries. Any frequency increments are allowed as REW fills in the blanks.Is it possible to transfer the factory data to a spread sheet or whatever file type that REW uses?
Download a mic cal file and drop it into Windows notepad to see the format. Create a file in notepad and save it, then change the extension to .cal. Load it into REW and examine the files graph for errors.