Run, do not walk, to request from your library a copy of Hermanson's "Bioconjugate Techniques." It is pretty nearly the Bible of modifying biomolecules.
I know how to do the opposite of the reaction you want, if that helps. Phenylglyoxal derivatives will condense and cyclize with arginine's guanidinium group. I used this reaction to specifically label arginines in an antibody with azides, using azidophenylglyoxal.