If the GM will let you strap a shield to his tail/forehead and make shield bash attacks, you could spend a feat on Martial Training and teach him how to use Iron Tortoise maneuvers. There are a few strikes in Iron Tortoise that have a 'taunt/aggro' rider effect on them.<br/><br/>This is an exceedingly silly visual, but it's the only reliable method of forcing enemy attacks on a target I know of. And Iron Tortoise requires the use of a shield/shield bash to initiate them. It's a pity you didn't get an ape instead - lower natural armor, but they could be taught proficiencies and they'd definitely be able to carry a shield.