Hi Mendel,
you do NOT need this "Expansion Voice Editor"!
The Yamaha Expansion Manager (YEM) has his OWN Voice Editor built in:
You have to make a new, empty Pack in YEM (My Packs - - - > Create Pack) OR use an existing (NOT copy protected) Pack. IN this Pack make a new, empty Custom DRUM Voice. Then simply double click this new, empty Voice, and you will be able to import your own Wave sample files (one for each key). The format of the Wave files should be: 16-bit / 44.1 kHz / Stereo (. wav /.aif /. aiff).
To prevent the sound from stopping, when the key is released, please click on "Receive Note Off" button.
Best regards,
Chris