Yamaha DTXpress/DTXplorer/DTXtreme

..but very excited to pick you brains, I've had a DTXpress for a bunch
of years and have really only used it for practice, and such, but,
now, being more adventurous in my old age, i want to start using the
DTXpress to trigger keyboard sounds/notes form my keyboard players
Micro Korg (i'm running MIDI out of the DTX and into the
MicroKorg)...I'm really confused on how to start the set up of this. 
Does it have to do with building a new "kit"?  or is this even
possible.  I mainly want a pad to trigger a note on the keyboard  I'm
using 2 cymbal pads and the BassDrum pad with my acoustic set.  

Sorry if this is very elementary, I'm just not too familiar with the
MIDI setup.

Thanks a lot!

Matt D