hi,
thanks for your help, it works now!
i used new_conversation and [::ChatWindow::For $chatid]
a couple of screenshots:

(showing original text)

(hiding original text)
i will upload it to my webspace and add a link on my original thread once i have commented the code and tidied up any loose ends...
i found something interesting when writing the part to translate incoming messages (using chat_msg_receive).
i am using chat_msg_send to read the msg, send it to google, and replace it with the translation (and some formatting). this adds a slight delay in the translated message appearing in the window.
i found that amsn interprets these delayed messages as having originated from the person with whom i am chatting, not myself. this caused the script to interpret my text as having came from the other person, and activated my chat_msg_receive script, which caused a double translation to appear on my window (though the outgoing text to their window was fine).
i had to create a $chatid.lastmsg element in the config array and use
if {$msg!=$::myscript::config($chatid.lastmsg)} {code}
to get around this.
anyway, thanks again for your help!
g