how to use DefineMethodSpec to define a generic method instance for called in IL

Hi,

i need to instrument generic method. Be more clearly i want to write IL to call the instrumented generic method when jit compile start. but now i don't know how to define a generic method that can be called in the IL. i know it need to use DefineMethodSpec to define the methodspec. but how to use DefineMethodSpec? how to setup the parameter pvSigBlob forDefineMethodSpec?