i understand,
i'm not familiar with the MSNC protocol and with scripts but i think there IS a documentation of it (probably not official
):
http://msnpiki.msnfanatic.com/index.php/MSNC:File_Transfer
this site gives a good view of how the protocol works i guess (too bad the examples are 'under construction')
as i get it right, you should recognize the invitation message (to maybe open the download childwindow), (the handshaking is not important in this matter) and then read the 'offset' field and the 'data length' in the file data messages to make a good progress bar, and also beware if the message is split (to make a progress bar of the complete file and not only of a split piece). also recognize the bye request when a filetransfer is stopped before it was completed or something like that.
i know and i'm sure that it's not that easy as i say, but i think it makes a little an image of how it works i guess (if you didnt found it before offcourse), i also dont know how much of the protocol you can read with the scripts (if it's not possible with scripts, i would ask Patchou to help us or make an own download manager
), i want to look at it too but i dont have experience in making scripts for plus and now i defenitly dont have time (but normally i have time a few weeks later) but i do have experience in working with transfer protocols (TCP, UDP..)
for the layout, the screenshot was just an example, it would be also good if it was in a separate window like the standard download manager in firefox (not embedded in the chatwindow) or maybe at the right side of the chatwindow (because i thought it would be possible because the 'grouping conversations' tabs are also part of the chatwindow, at the left or top side of the window), but i dont know if thats possible with scripts either
/ 
