Example usage of AX in PHP OpenID

Question

I'm using JanRain's PHP OpenID library. It comes with example script which is using SReg extension. But I want it to work with Google (and it works for auth actually), but Google uses AX (attribute exchange) instead of SReg for additional data. For some reason, JanRain's library is missing AX support in example script, and code comments in AX script are out of my understanding, though comments in SReg script are clear as 1-2-3.

Does anyone know how to implement AX without too much pain?