I got my Treo WX at the end of October, and ever since then I have been trying to figure out how to use AIM on this thing. Well, I think I finally figured it out --
www.ebuddy.com. It has a mobile version. Just go to the website on your treo, and you will be able to get on AIM from there, and it's awesome. The best part -- IT'S FREE!!!!!!!!!!!!!!!!!!!!!!!