When importing a sample into ST2, part of the the file name would determine what velocity would trigger the sample. Using a "V" followed by the velocity value did the trick.
For example, "C1 v85.wav" would be triggered by velocities up to 85.
But the instructions in the ST3 manual don't mention anything about setting velocity levels - nor does the video tutorial. Is this function now beyond our reach?
If worse comes to worse, I can simply set the instrument up in ST2, and then import that into ST3. But I hope that isn't necessary!