Extra modifiers (Slash Command)

/extra_modifiers [mod1] [mod2] [mod3] [mod4]

Allows setting up to four extra modifiers on a controller/gamepad.

These (currently) only work when no other modifier is pressed
Recommended for XInput users is /extra_modifiers LBumper RBumper
The up-to-four 'Extra Modifiers' are just additional inputs (either keys or buttons) that can be treated as modifiers when no other modifier is pressed. So for example, you could do /extra_modifiers LBumper RBumper to make the bumpers modifiers on your XInput gamepad. You could then use (for example) LBumper+Joy1 as a /bind (but also still be able to use LTrigger+LBumper as a separate bind).
The 'Extra Modifiers' aren't limited to just gamepad buttons, however! If you want, you can bind any key on your keyboard as one (but note that due to some things that still need refactoring, you can't bind a specific Shift, Ctrl, or Alt key on your keyboard yet).
There are other convenience aliases which you may have already noticed (e.g. LTrigger, LeftTrigger, RightBumper, StartButton, AButton, and so on).

Example