L.
I don't know how they do it, but the Attorney General somehow tracks a NCP's employment information and sends them the withholding letter. Might not be as timely as you would like, but they will do it. I know first hand.
If you know already where he is employed, you should send the Attorney General that information of his new employer's address so they can go ahead and send that letter to them to begin withholding.
Really, there is no reason to get an attorney for a thing that will be resolved shortly -- just not tomorrow. If you really need one, I have a great family law attorney that I am currently working with. Contact me and I'll send you her info.
Otherwise, good luck!