Maybe I'm missing something, but it looks like trivial.
Dim ByteToSend As New Byte(3)
ByteToSend(0) = 49
ByteToSend(1) = 48
ByteToSend(2) = 48
myComPort.Write(ByteToSend, 0, 3)
Or these were just typos and I'm completely off-subject.
Anyway, hope this helps.