Для своих настроек в IceWM делаю так
# Audio volume: Up/Down
key "Alt+Ctrl+KP_Divide" amixer -q sset Master 3%- # lower volume
key "Alt+Ctrl+KP_Multiply" amixer -q sset Master 3%+ # raise volume
# Audio volume: mute/unmute
key "Alt+Ctrl+m" pactl set-sink-mute 0 toggle