Hi STE,
Nothing like resurrecting an old post
I have not lagered either, but what follows is my understanding.
As the guys say, eight weeks will be fine and it will result in a better beer if done properly. In a cube will be fine if the beer is fully fermented before you rack into it then lager the beer.
I assume it's being fermented at lager temperature with a true lager yeast. Make sure you read about diacetyl rest (and, in general, fermenting lagers), and keep the beer as close to freezing as you can while lagering.
It'll be fine.
Cheers,
Oliver