Your best approach is going to be to bring the gun back using an importer/customs broker/ffl. I don't know if John Boyd in Houston provides this service, but he certainly would know how to do it. A little closer to you, but still on the wrong side of the Red River, TRI in DFW is in this business (handling customized imports). Their website is http://www.trimports.com/import-services.html and their phone number is 866-419-6271. Never done business with either of them (but I have friends who've bought stuff from Boyd and speak well of him).

From your address you appear to be a bit of a Boomer Sooner, but I'm afraid you're going to have to rely on the Texans. And starting now you'll never get this done before football season . . .