Int 21 Fn 5FE3  - Lantastic - Set Message Service Vector                   [N]

   AX = 5FE3h
   ES:BX -> FAR routine for processing network messages

Return: CF clear if successful
   CF set on error
       AX = error code

Notes: handler must chain to previous handler as its first action
   on invocation, ES:BX -> just-received message

See Also: AX=5FE2h