The only criteria to get this to work are that you need to have the "Pending Trades" Home Page module somewhere on your home page and you need to have the following script in your footer.
Here is the code that must be placed in your footer:
(Make sure that your advanced editor is set to "off")
If you are using my previous trade alert popup (see here) you should remove that one if you are going to use this one.
You can see it working on this test site:
Login as the "Dolphins" password "dolphins"
Let me know of any issues.
EDITED TO ADD
March 9, 2009: I added on option to add a custom message to the popup when a trade has been proposed to a team. For example replacing var popupTradeMessageToMe = ""; with
var popupTradeMessageToMe = "<img src='http://www.habman.com/mfl/apps/js/images/tradesign.png' />";
Will will replace the normal trade offer announcement with this image
Thanks go out to "thehohiostate" for creating the image.