I just did a quick internet search and found this. I didn't look at the *.ins files themselves, but maybe there's one for your model. This ^ .  I use the insert button (computer keyboard) to put in an event used, and then click on it to change the "Kind." EDIT Just took a quick look. Here's the instrument definition header.  Also, it looks like the author has drum keys defined, too!  ; instrument define Korg Pa4X for Cakewalk/Sonar ; written by (Anton Janosik) www.korgpa.sk