I found this -
https://help.aol.com/articles/AOL-for-Mac-OS-X-Installer--FOR-EXISTING-USH1191
It's AOL version 7.4 - from 2005.
And, I just tried it. It's a PowerPC app, so you can't use it on Lion. but will work with 10.6 (if you have the rosetta installed on 10.6).
I actually had a copy of that installer from when I used to use AOL, so if I recall correctly, it's the last version before the AOL Desktop versions.
I'm guessing that you need the Dialup support which would have been part of the AOL app, but dropped in the Desktop (I think!) - If that's correct - good luck on actually finding a dialup to call into. This area (Delaware/Maryland) used to have dozens of alternate AOL dialups. I last checked about 6 months ago, and there's only one or two are left, and it is a lot of hope just staying connected for more than a few minutes (I tried it out after several years since I last used dialup!)