I believe that any sound / preset in HSSE that has “VX” in its name has an assocaited expression map.
Load up HSSE in an instrument track and select “Acoustic Bass VX”
over in the inspector to the left, click on the “Expression Map” tab, it should say “no expression map” in grey
(I think they avoid auto-loading the maps because it would be really weird if you weren’t expecting it!)
Left click on the words “no expression map” and in the dialog that pops up, select “Import Key Switches”
In the window that pops up (for this example) you should have four mappings configured for you (shown in the middle of the screen). I don’t know what your relative expereince level is so I’ll appologize if I’m tilling familiar ground here.
What this is telling you is that if you reach down and press “C#0” on your MIDI controller, the sound will switch to the “Open Hard” sound. If you press “D0” it will change again to the “Dead” sound.
You can see a monitor of sorts pop up in the inspector with green triangles on it? They should respond when you press any of the four keys shown in the middle section under (remote keys).
Remote keys are what SB calls the keys you use to trigger the new sounds. \
If you want to add more choices, use the little plus key in the center section.
You can use the Art 2 through Art 4 colums to layer up more stuff for it to do when you hit the assocaited remote key.
I sure hope this helps! Have fun!