That is a very old link and the site still does not forward old links properly....
To find the script, go to the main site (www.msgplus.net) > Downloads > Plugins.
There you type 'SpeakAll
' in the searchbox.
In the same way, search for 'translat
' (no, it is not a spelling mistake, search for 'translat', not 'translator' or 'translate'
) and you'll find a lot more scripts which are capable to translate chat text.