I'm posting (with permission) something Dr. Anderson recently said in email correspondence:
I agree that the RC objection typically involves a level confusion: conflating the rule of faith with the special revelation it identifies.
So it's quite possible to state SS in a way that is not self-refuting but still preserves the core concerns that motivated the Reformers. Take this statement, for example:
SS1: The Bible alone is the Word of God.
This would certainly distinguish the Protestant position from the RC position (as per Dei Verbum). But it doesn't require that SS1 itself be taught in the Bible. It could be justified on other grounds: part biblical, part extra-biblical. It doesn't face the obvious epistemic self-defeat that, say, Clarkian Scripturalism does.
SS2: The Bible is the only infallible rule of faith and practice.
Again, this distinguishes the Protestant position from the RC position. But even if SS2 weren't taught in the Bible, there would be no self-refutation unless the further claim were made that the epistemic ground of SS2 is infallible. (Sproul says somewhere that the canon is "a fallible collection of infallible books". I take it he's making a similar point.)
SS3: The Bible is the sole final authority in matters of doctrine.
Once again, this would separate the sheep from the goats. But even if SS3 weren't taught in the Bible. the charge of self-refutation wouldn't apply unless (a) the Bible taught something incompatible with SS3 or (b) SS3 were conjoined with the additional claim that SS3 is on an epistemic par with the doctrines taught in Scripture.
And so on for any other formulation that could do the work the Reformers wanted SS to do.