[Haskell-cafe] Tutorial on how to use multirec

Hello. I am writing a compiler in Haskell and need some tools to work with abstract syntax trees (like annotating them with source positions and other things). I have been pointed out to the multirec package. I have found some information about the package, but it is too dense to read and understand, as the ideas are presented from a theoretical point of view. So I am looking for something more light, as tutorials or simple applications that illustrate the use of the package. Any help? Romildo