Well, it can easily be found either running the base CB-Emu.exe program, or MessExtra.exe from the relevant sub-directory (the first exe just submits the second if the computer is handled there). Folder list should be toggled on (on the left of the GUI) and the Maestro A is listed in either of those folders: All systems, Chess_All, Chess_Saitek.
If you don't see it, most probably you are not using the expected package, or are using a not recent enough one. Check here for the "CB-Emu Pro" item and "CB-Emu" download link.
Hope this helps!