There is the nowplaying plugin for wa2, but even thought that will let you save the current song to a file, (for aim it would be the profile.htm file), there is no way to force aim to refresh that anyone has found. (this topic comes up a fair bit) So the best you can do is to host the file that something like nowplaying saves, and then place a link to it in your profile. (you can have it open in the profile window, but doing target="_self" I think it is).
there is a link to now playing at the bottom of that page. (there are several equivalent plugins around)
[edit: do a forums search for more information.