Step 2 - Left-Side Mirror Alignment: Set your left-side mirror so that as soon as the passing car's left, front headlight disappears from your rear-view mirror, it appears in your left-side mirror.

You might need to make some slight adjustments to your side-view mirrors to make everything line up perfectly. And pulling up next to a line of parked cars (to simulate another lane of traffic next to you) is a good way to do that.