Harvesting Lager Yeast from conical

I've read a number of different techniques concerning harvesting yeast from a conical but I believe most of those were ale yeasts. My question concerns harvesting lager yeasts and what others have found to be the best method. I want to harvest the most viable, robust yeast population and I'm not certain when would be the best time to harvest since lager yeast are often classified as bottom fermenters.

What have others found to be most effective?

Jeffrey

I would imagine if you did an initial trub drop, then waited till the end of active fermentation you should be able to take most of the cake, then just wash as normal.