CxxWrap and IO and iostream

I love CxxWrap, but I can’t find anywhere in the tutorials or documentation how to wrap a read/write C++ method into Julia.

More specifically: the C++ code I want to wrap has an object X with methods X.write(ostream &s) and X.read(istream &s). How do I implement, on the Julia side, read(::IO, X) and write(::IO, ::X)?