Follow this link

http://toc.oscar.aol.com/

Use the Register button to sign up for a screen name. Works pretty much on any computer with internet access but has some problems with very secure firewalls

You only need one screen name and can log on using that screen name from any computer connected by going to this website.

You can also use AIM Express in the same manner. I just can't find the direct link. However you can access the AIM Express START button from this link.

http://www.aim.com/get_aim/express/aim_expr.adphttp://www.aim.com/get_aim/express/aim_expr.adp