There is a book (which line always makes my husband panic, looking at the overstuffed bookshelves reaching the ceiling) Tan Your Hide, by Rodale press. I've used it, and many of the difffering tanning recipes. For any leather you might possibly want to wash, ever, use Gluraltehyde (sp?) it's the one that leaves the suede a rather yellowish colour. Last place I found it was in Canada, but has been a while. I really don't recommend alum on large hides, cuz it leaves them really hard to work into softness. Or maybe i'm a wuss. Freeze the things until you decide whether to do it yourself, or hire a tanner. A whole sheepskin is a very ambitious first project. Before tackling that, find some rabbit skins. (at the local butcher) and try that. You can generally get them for free. It is a good way to practice.