I'd likely use the Troop subtype. Hogs and boar are Medium creatures and the troop take up a Gargantuan space (though can fit through spaces a Medium creature can). Dire boar are Large animals (Dire hogs may or may not be smaller, but still probably Large), which means you'd need them to take up an even bigger space.
Someone did make a Feral Hog Troop (I don't think it's from anything 'official', but then neither is yours). They are based on hogs/boar not dire hogs/boar, so only Medium creatures. You can tweak it up (and add abilities based on HD for dire upgrades. You can take a look and take any inspiration.
