Thanks for the post and for your kind remark about the course. I hope you find the remainder of the lectures informative.
We don’t have much material on Callicles so what can be said about him is to a large extent speculative. (You might find it helpful to take a look at http://plato.stanford.edu/entries/callicles-thrasymachus/)
All the Sophists in one form or another made a distinction between the natural and the conventional. Many of them regarded law as falling on the conventional side of the distinction and Callicles would seem to be of this opinion too. It seems to have been the case that Callicles regarded law as a device by which the weak imposed on the strong, a view sometimes attributed to Nietzsche also.
Your comment on the inculcation of morality via training is, I believe, largely correct. Callicles would seem to have regarded social norms as simply another form of training by which the strong are hamstrung.