Controller modifiers (Slash Command)

/controller_modifiers <first> <second>

Allows setting two controller buttons as modifiers on a gamepad

On non-XInput devices, when both of these are pressed together, the controller will enter virtual mouse mode
The arguments are the button numbers to use (from 1-24)
Recommended for XInput users is /controller_modifiers 7 8 (the two triggers, since these are currently hard-coded as virtual mouse mode on XInput)
The 'Controller Modifiers' are special, as pressing them together enables Virtual Mouse Mode. They do work as bindable modifiers just like the pre-existing three.
There are other convenience aliases which you may have already noticed (e.g. LTrigger, LeftTrigger, RightBumper, StartButton, AButton, and so on).

Example