Contact Valkyre Tactical and ask them to get the gun for you. They are a central Ca company that modifies 1911's among other guns to get them in state under the "Single Shot Exemption" in the safe roster law. Once the gun has been converted and legally transfered to the new owner, the owner converts it back and sends Valkyre back the conversion parts. Many people have taken advantage of their service on 1911's, Springfield XDm's, Gen 4 Glocks, and other "off list" guns. Their cost for the service is reasonable, and they are stocking dealers for several makes as well.

valkyrietactical.com

There is a thread on Calguns.net about the conversion process and the laws regarding it.