Found me a recipe that calls for cultivated Sierra Nevada yeast - how do i do that ??? how do cultivate yeast from my beers ( just looked at a SN, couldnt see any yeast on the bottom of the bottle ) ??

Save yourself some trouble and get WY1056/WLP001. Same yeast. If you want to culture yeast from a bottle, make up about 100 ml. of a 1.020 wort. After carefully decanting the beer from the bottle, flame the lip of the bottle and pour the dregs into your starter wort (or pour your wort into the bottle). Let that ferment out, decant the spent wort, and pitch what you've got into a qt. or 2 of 1.030 wort. You may need to repeat this last step in order to get enough yeast to pitch.