Thanks, guys.
sperry, I dug out a hole for the lift so it would be flush. It was kind of scary -- I'd never poured concrete before, wasn't 100% sure this was the right use for this kind of lift table, and the first step was going to be to cut a 5'x5' hole in my nice garage floor. I rented a walk-behind concrete-cutting saw and dug a 16" deep pit. Now that it's done, there's an 8" thick reinforced pad underneath the lift. The walls for the pit that are tied in to the surrounding pad with rebar. I had to bring the concrete sacks home in two loads to avoid destroying my Jeep's suspension. The mixing and pouring took an afternoon. Finding out that it was the right depth (and seeing the lift go up for the first time) was pretty satisfying. When you get concrete wrong, it's a real pain to tear out and do again.
Just getting the thing home was an adventure. Since I'm frugal, I rented a truck from Home Depot -- $20 for 90 minutes. Getting the thing down by myself was tense. The lift table itself weighs 950 pounds.
This video shows some pictures from the installation. You just have to weight through a minute or so of cheesy 'presentation.'
Here's a clearer look at the whole deal. You can see it's shimmed up to get to the right level. Better to go a little too deep than to not go deep enough and have it never be flush.
It also works as a work surface. It's also useful for getting heavy stuff into the back of the Jeep.