If you are genuinely processing Compass data which was originally measured in feet and inches, then use that format in your Therion data files and just tell Therion which units your data is in. If however you are working with data that was stored in Compass but originally surveying in metric, then you can use my cave converter program to convert Compass data to Survex data. Not quite Therion format, but very close and you can cut and paste the numbers from the Survex file into Therion files. This will convert the data back to metric from the imperial units saved in a Compass file.