We have added a new function called Toggle Alt/Shift Action under Special > Generally Useful Functions in the Hotkey Editor (Preferences > Interface > Hotkeys/Menu Editor). This function lets you define a hotkey to toggle between the Azimuth/Twist and Tumble/Zoom viewing modes quickly in Perspective view.
Previously, this switch could only be achieved by setting the Alt/Shift Action option in the Viewing section of the Preferences > General Preferences window, or by accessing the NavBar on the ViewCube.
Hotkey toggles between those two modes on the NavBar