I\'m using .net 3.5 named pipes and my server side is :
serverPipeStream = new NamedPipeServerStream(\"myPipe\", PipeDirection.InOut, 1, PipeTransmissionMode.Byt
The problem is BinaryWriter doesn't have a BeginWrite function so, as suggested here, you could write to a MemoryStream and then use the its buffer to pass to the BeginWrite function of the pipe.
BeginWrite
Hope that helps.