The ShuttlePro has 14 configurable buttons in addition to the Jog and Shuttle wheels.
To assign these buttons to shortcuts use the "ReplayA" to "ReplayO" Key options when creating a Shortcut in vMix.
See Shortcut Reference for a list of Instant Replay related functions that can be assigned.
A number of keyboard shortcuts can be configured using the existing Shortcuts feature in vMix.
For a full list of what is available see Shortcut Reference.
The mouse scroll wheel can be used at any time in the following ways:
With Shift key pressed: Slow down or speed up playback
With Ctrl key pressed: Move backwards or forwards one frame at a time.
With Alt key pressed: Move backwards or forwards one second at a time.