plugin for outlook express

hi
i am interested in developing a activex plugin for outlook express.
this should be like a button on the outlook express toolbar-say xmit.
when clicked this button should pick up the text from the message window of outlook and send it to a desired serial port.
similarly a button -called say recieve - should when clicked recieve data and display it in the outlook express message window!!
i am connecting a hardware to the serial port which encodes the data. this encoded data is to be recieved and displayed in the message window.
can some one tell me how to do this/send me a sample code for the above/refer me to some other source, please??
i am an absolute newbie to activex programming , but want to get this above done for testing my hardware effectively!!
can someone help me??
thanx