Unfortunately, you can't. There are experimental systems that convert 2D broadcasts into a kind of pseudo-3D, by using complex maths to 'guess' the distances between objects on screen, and digitally tweaking the image in order to create the illusion of depth.
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It's a complicated business - and as you can imagine, this kind of system requires a massive amount of processing power. Sadly, the results are not really worth the effort - perspective often looks artificial, and sometimes that digital guesswork falls a little wide of the mark.
Panasonic 3D TVs don't offer this kind of 3D processing on the fly because it's not yet reliable enough to provide the results you expect as a viewer. What you do get, though, is superb 2D picture quality in full 1080p HD – so why not sit back and enjoy the view?