[rwallace]

'We' is a bit vague here. Are you this guy's boss?

If not, you shouldn't start a feud with a peer. It doesn't do anyone any favors. Get on with your job and let everyone else get on with theirs.

If so, decide whether the issues in question are really that important. If they aren't, cross them off the list of rules to follow. If they are, order him to do things the company way. If he refuses, fire him for insubordination.