It looks like a standard 12" rough-in toilet. There's nothing in those drawings to suggest that you wouldn't install it the way you would any other. There are slots in the porcelain on either side of the flange where closet bolts (that secure the toilet to the floor) will go, so you're not going to do any "centering", although that will, I suppose, be the net effect of installing the toilet onto the closet bolts.
As far as I can tell, you're just going to drop the wax on the floor and drop the toilet on the wax (subject to following all the manufacturer's directions, of course).
The outlet hole is always going to be smaller than the closet flange, except maybe on the Caroma brand, which features a huge trapway. It is true that this one is a little smaller than many: The Kohler Ingenium flush uses a 2" trapway; Toto uses 2-1/8".
Presumably, the manufacturer has installation instructions for the thing. Always, and I mean always, read them thoroughly. Too many folks, especially many very-experienced folks and pros, have to start over or worse because they failed to just read the darn installation instructions.
Here are the LBL install instructions. They are less-than-detailed. However, there are no surprises in them: http://littlebottomline.cdn.weboluti...-LBL-20131.pdf
A couple of tips that Terry often offers on the forum: First, if you want a nice secure installation, chuck the closet bolts that come with the thing (if they do) and get a nice set that has two washers and two nuts per bolt. Put the closet bolt where you want it, and secure it in place with one of the washers and one of the nuts. Then, when you have carefully placed the toilet on the wax and closet bolts, and have smushed it down into position, use the second washer and nut to secure the toilet to the flange. Second, most pros put the wax on the floor and drop the toilet on the wax; manufacturers are split on whether to try to apply the wax ring to the bottom of the toilet and then set it -- generally you're going to have a happier time if you just put the wax on the floor around the flange, even if the manufacturer says otherwise. Third, one wax ring (with no plastic spigot) if the top of the flange is anywhere above floor level. If below floor level, two wax rings (bottom one with no spigot, top one with a spigot) or a double-ish-thick one. (Typically, a flange installation to code mounts the flange on top of the finished floor and secures it through the flooring to the subfloor, but some builders, to save time and money, mount it on the subfloor and tile around it.) Fourth, when you caulk the toilet after installation, use Polyseamseal, rather than silicone caulk. It will be easier to remove and leave very little residue when you pull up the toilet for replacement after your child outgrows it.