Data Contract Serializer Hook in WCF

I have a need to do some data changes to the data being returned by a set of WCF services either during or post the serialization process by DataContractSerializer. I know about the parameter inspector, but need to do it a bit past this point. My understanding is WCF allows things to be done in layers so we can hook here, but do not know how. This project is to create a prototype of a wcf service where we change a value during or after serialization. This project must be in c#.