I\'ve been doing some work extending the WCF pipeline of my service using mainly IOperationInvoker to implement my own functionality.
IOperationInvoker
I am currently using
I believe you need to be linked to OperationContext not HttpContext. The answer to similar question is already presented here.
OperationContext
HttpContext
Basically you just need to implement IExtension and plug it into WCF. Step-by-step example can be found for example here.