I thought the 2v2 ladder system still used Bayeselo. Coulon did release third-party software you could use to make Bayeselo calculations here:
http://remi.coulom.free.fr/Bayesian-Elo/I can't find good libraries for it, though, but if someone could point me to a place where I can find the theory/formulas/algorithms, I can whip up a library in Python, Java, C, or C++ pretty quickly.