Well, I'm back from running my errands. Here's a video - a bit wobbly - but her instructions are good: https://www.youtube.com/watch?v=5_W84cH5hfg

I have used this method before. The only difference being is that I drew the sewing line and then cut the extra off after sewing the miter - kept me from having to deal with the bias. Plus, if you make a mistake, you can get the dreaded seam ripper out and try again!