Kylotan: I figured out enough of the drum map file format to create drum maps, but there are parts that I'm not sure about. I can share the file format if there is interest. It should be enough to read/write drum maps with all parameters.
I could have written a more complete editor for drum maps, but except for the part of creating the initial list with the instruments, I can live with the editing options inside of Sonar.
Elffin: Exporting an excel sheet as a text file that can be used with this tool should not be much work. If you have two columns, first with the note number and second with the instrument name, and then export with = as separator, you have an instrument map.