Key function "quiet" (lower volume to 10 or 25%)

[kfsone]

Mute is very nice, but sometimes what I want is just to turn the volume down for a while.

I play WW2Online a lot, and I often want to listen to the environment instead of the radio. However, its very inconvenient simply cutting the radio out altogether. What I'd ideally like is to turn the radio volume down N%; either to 50 or 25% of its normal setting. When I let go of the button it goes back to normal. (I'd also like to program a key which toggles between quiet and loud states)