Starting with v1.1.7, you can use the standard MIDI volume-expression controls with Unify:
These MIDI responses are disabled by default. To enable them, go to Unify's Settings view. Near the bottom you will find a row of four check-boxes like this:
The first two checkboxes enable interpretation of MIDI CC#7 and CC#11, respectively. Note that when these boxes are checked:
(In a Multi-timbral setup, this may be the opposite of what is needed. Click the link for details.)
Regarding the second pair of checkboxes, see Changing patches with MIDI.