Washing yeast is actually really easy. The day before I boiled a pot with 3 pint jars and a pyrex bowl. I put the jars in the fridge over night and let them cool down while being sanitized. When you have racked the beer off of the yeast, you are of course left with the yeast cake. I dumped the sanitized water from the jars and pyrex into the carboy and shook it around to get the yeast back into suspension. I then used my auto-siphon to rack the yeast over to the mason jars. My process I adapted from a post on Homebrewtalk.com about yeast washing - it worked out great!