Although somewhat general in nature, we found a manual online at http://www.cedarbureau.org/cms-assets/documents/45094-350971.cmbrochure2011.pdf produced by Cedar Shake & Shingle Bureau that could be helpful. We have seen several different fungicides used to control moss. Roofing consultants have advised us that simply washing annually to clear debris and keeping branches off roof are the most important maintenance activities for a cedar roof. In drier climates oils or other protective products can extend the life.