You don't need a shaman. You just need to learn. All the information is here, just do your research and feel free to ask any questions along the way. The better prepared you are, the better the experience will be. I have summed the entire experience up once or twice on here before, in step-by-step manner; I'll see if I can find one of those posts. I have treated a friend who has psoriasis, with kambo. I looked in my book of Tui Na Chinese acupressure massage for the acupuncture points that were said to treat skin conditions like psoriasis. I did one session on him and he reported that it cleared up a good amount, upon which it later returned because he did no further therapies.
Psoriasis is an autoimmune disease of over toxicity. You want clean the liver and gallbladder as well as the blood. I have sent him info before which I will try to retrieve. Start taking detoxifying herbs like dandelion, milk thistle, red clover, cleavers, burdock, artichoke, etc., and eating clean, a large ratio of plants foods in your diet. You can consider fasting as well and herbal enemas. Information on both of those therapies are on this forum, though they may not be in the most accurate sections, because I just recently added a bunch of new sections to the forum. Kambo does help with psoriasis because it is deeply cleansing.