I had the same problem with you. Later on I find out that you need to load a sfz file in order to assign diferent sounds to different keys. The sfz file would also list velocity switch infomation. You can go to your C drive-program file-Cakewalk-vstplugsin-sessiondrummer3-contents-kits-(any of the 12 folder, for example bass drum). Inside this folder are numerious sfz files. Each of this file are assignment of a particular catogery of percussion or drums. You can open them up by right click-open and view the detail info. It is possible to can create your own sfz file. The easier thing to do is mix and match these sfz file and create some unique drum kits.
Choo Shi-Hwei, Malaysia
Sonar8.5, Ua25ex, M-audiophile 2496, i5 CPU, 4 G RAM,W7 64bit, A Pro500