User blog comment:DJ TechnoBrat/moving from one cover spot to another in a gunfight/@comment-2088714-20100606023726

It looks like I can do what I want by pressing Left-Stick-Down (on xbox) to start crouching before I get to the cover, then right bumper to use the cover, then right bumper to disengage and move to the next cover.

But I really thought there was some kind of "run while crouching and dive behind cover" thing that they tought us. Maybe I'll restart a new game and try that mission again.