You can't hook random buttons on the persons keyboard, but you can hook certain activities in the game, which are sometimes the same thing.
These can be hooked with FM_CmdStart.
PHP Code:
IN_ATTACK
IN_ATTACK2
IN_BACK
IN_CANCEL
IN_DUCK
IN_FORWARD
IN_JUMP
IN_LEFT
IN_MOVELEFT
IN_MOVERIGHT
IN_RELOAD
IN_RIGHT
IN_RUN
IN_SCORE
IN_USE
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