It's tough to see a sola scriptura justification for infant baptism.
I certainly don't disagree, but paedobaptists who are otherwise Biblio-centric in their approach to doctrine seem to think there is. It's sadly obvious that it's a case of reading their tradition into the text, but it's not a primary issue, or one I'd break cross-denominational fellowship over. If I were an elder I couldn't admit someone as a member to my congregation who hadn't been baptized the right way, but I have no problems recognizing them as a brother. Some of my biggest "heroes", from Calvin to N.T. Wright, were or are paedobaptists, and while it's a shame, I find a way to get over it. There are of course other issues I disagree with them on, some of them even more severe than mode of baptism.
It's funny though, I don't know why anyone would WANT to find paedobaptism in Scripture. The circumcision of the heart is a much more powerful parallel sign to OT circumcision than infant baptism is....I get the warm and fuzzies more over that than sprinkling a baby with some tap water...
And I don't know that a couple strains of something akin to universalism would prevent holding to sola fide. I've struggled with Karl Barth often, and I think when it comes down to it he was a believer and probably held to sola fide. He was still a pain in the ass, but given what he came out of...