Have another look at the options
Have not used rocketdock for a while but I'm sure there is an option to minimize to the dock
If not Rocket dock it may be ObjectDock that gives this functionality
This is straight from the online manual 6. Minimized Windows
If you have enabled "Minimize Windows to the Dock" in General Settings, your minimized windows will show up as icons on your dock. These window icons can be dragged around for rearranging, but cannot be deleted or closed by dragging off the dock. In Windows Vista, they will be rendered as a real-time preview if you have Desktop Composition enabled in your Windows performance settings and the ability to use Aero Glass.
You can open or close a window by right-clicking on the window icon and selecting "Open Window" or "Close Window." By default the window will be opened if you simply click on it.
Oops just re-read what you're after - hae a look at the available add-ons for object dock hey have one to replace the start menu completely - It may work with Rocket Dock or maybe you may want to check out object dock