The donor file can actually be the WZR file you are working on as long as you have saved it before you open it in the Browser. But it actually doesn't matter what kind of file you use. You just need the IR for the particular button you have created. Open your donor file (any MX remote or CCF file). Then drag the "Learned Data" from the button you need onto the "MX-810 Action List." You could also use hex if you have it. As long as it is the right IR code, it will work. I have seen the following: "Learned Data," "Preprogrammed," and "IR CODE." All have worked the same for me.