This is an Xposed-module! You will need a rooted device with Xposed installed: http://bit.ly/1hCaq32
After activating the module in the Xposed app, please reboot your phone. Afterwards, you'll be able to press the volume up/down keys on your device to display the statusbar volume-slider.
In order to slide down the expanded volume panel, please start the swipe-gesture slightly *below* the volume bar (where the ActionBar normally sits). Alternatively, you can also single-tap this area, and the volume-panel should slide out automatically.
The module is free without ads. After 14 days, you'll need to pay $0.99 if you want to continue using it.