I attach one of these:
http://www.tandyleatherfactory.com/search/searchresults/8122-00.aspx?feature=Product_1&kw=slicker
to a drill. I put my drill in a vice clamp. I turn the drill on, hold the leather tight, and run it through. I like Echo Flo Gum Tragacanth. I rub a bunch into the edge, run it through the wheel, edge coat it, run it through the wheel, wax it, run it through the wheel, and then sheen it. Makes lovely edges!