I am confused about what you mean by "temper," why you'd need to artificially melt it, because unless you're using shea that's been heavily refined, it shouldn't take more than a minute for it to melt in your hands.
Having very dry skin, I've used shea for years. I coat my body with it from head to toe a couple times a week, and use it in my hair as well. I pick up a blob, put it in my palm, rub my hands together and it's all melted and creamy. It's fast.
I have noticed that some of the store bought tubs of shea butter aren't really shea at all but a mix of garbage with a little shea mixed in. And those that are all shea, have been refined so much, that the shea is ruined; it doesn't melt, it's gritty, it's ick. Plus all that refining and processing kills the E and whatnot that is naturally present in shea. The beneficial vitamins have been heated away.
Out of Africa is a great brand (unrefined, REAL shea), but I don't think it's available anymore. L'Occitane sells shea but they process it to death. After buying a bunch of store bought garbage over the years, I have found that sticking to raw unrefined in bulk is the best. Just shy away from the smoked stuff, unless you want to smell like a campfire.