Now, I have used the microwave to bake sweet potatoes before. I do not recommend this. Yes, it does bake the potato. However, it kind of dries it out. I just don't like it as well as oven-baked. But "steaming" them in the microwave works pretty well.
Here's what I did: peeled the potatoes (you can leave the skins on if you like them), cut the potatoes into small squares, and arranged them in a casserole dish. Then I added a small amount of water (about 1/2 inch for 2 potatoes), put the lid on, and microwaved on high for about 10 minutes.
Once they come out, you can eat them as they are, in squares, or you can mash them up. I like them mashed up with salt. You can dress them as you like: butter, salt, cinn