Yamaha DTXpress/DTXplorer/DTXtreme

I can't help you with the midi stiff (although I am fairly sure that
it is possible to do what you ask - hopefully someone will confirm
it), but the manuals can be downloaded from here:

http://www.yamaha.co.jp/manual/english/index.php

Just type in DTXpress and it will list the manuals for the different
versions.

Keith.