Actually, it's easier. Simply put in your desired travel dates. When the search results come up, on top of them, there is a display of the fares for +/- 3 days (whether you want them or not). Admittedly, it doesn't always display at the same time as the initial results do, so there is sometimes a delay of a few seconds where they don't display.

By the way, this thread will likely be merged into the new site thread.