Ok, after a lot of shaking of my head, I googled it.http://www.nzmp.com/cda/frontpage/0,...400077,00.htmlhttp://www.usaemergencysupply.com/in...reampowder.php
and a substitution charthttp://www.barryfarm.com/How_tos/wha...titute_for.htm
So, at home, you would need a container of suitable size, a motorised air system that has hepa filtration on the main air in, as well as chemical dryers so that it was well dessicated, a holding tank for the sourcream, and a pump and spray nozzle to inject the sourcream into the drytank as a suitable mist that is then dryed with dessicated air.
Hmmm, I think I would rather just sub it or buy it that do all that. Although, if you had the money, you could see if there is a turnkey type outfit that will come to you and set you up to go into production of sourcream powder. (if I had the money and space I can do just this with a mushroom farm :))