Ok, so I went to Walmart today and they had a funnel that has a measuring container on top and it has a lever that you turn it on and off. So you can turn the spout off, fill it up to a quart and then drain it. So, this way I can measure out the exact 4.5 quarts.
I was waiting for someone to tell me a trick though of why they're doing 5 liter bottles... I can't even think of a reason...