I haven't tried this in 2.0, but on 1.2.3 all you had to do was run through the wizard and set the WAN interface bandwidth to the limit you want, say 60Mbit, and then activate at least one other shaper action (like prioritizing DNS), and then the queues and rules that were made would accomplish that limiting.
You could use a limiter on 2.0 to do that, but you'd have to make sure that all of your traffic in and out of WAN was run through that limiter. Probably with a floating rule on WAN would be easiest.