Using time capsule as a wifi extender

I recently bought a 3tb time capsule primarily to back up my macs, but I presumed that it would extend my wifi network as well to another floor of my house. As it turns out this is quite challenging.

What I want to do is a Virgin Superhub as my primary router, power-line to my other floor then the apple airport time capsule as a wifi extender. Since the TC will be connected to the main router via powerline there shouldn't be much loss of speed/ping.

Any help is appreciated.