It will cost a pretty penny, but Steiner usually has Hank in periodically. I participated last year to add him to my SS OMLB collection and I believe it was $150 for flats/baseballs. Send them an e-mail and I am sure they will give you some info.
Better yet email Joe Groglio about it at: firstname.lastname@example.org. He's the rep at Steiner that handled everything last time for all the people that submitted through SCN, and I'm pretty sure he's doing it again for the next signing. I got 3 items done at the last signing and everything turned out great. Good luck!