Comment 13 for bug 871133

I found a workaround :D
With the command, you can control the volume: amixer set Master 1- (lower), amixer set Master 1+ (higher)
This commands can be set for the special keys you want: System Settings -> Keyboard -> Shortcuts -> Custom Shortcuts
Here you have to create two new entries: 1. Name: VolumeUp, Command: amixer set Master 2+ (I think '1' is too slow for change). The second one for VolumeDown. Then set the key for running this command by clicking on the line and type, scroll or whatever you want to use for volume-control.

The only thing which don't work is the quick-notifying (this bubble in the top-right corner) which shows the change of the volume.
But now it works smooth as hell :)