Here are the specifics on how to setup AOL on Mail as IMAP, using comcast might not work at all:
http://members.aol.com/adamkb/aol/mailfaq/imap/
How do you use AOL's IMAP/SMTP servers?
The AOL IMAP and SMTP server addresses are:
imap.aol.com (port 143)
smtp.aol.com (port 587)
Log in to the IMAP server using the appropriate AOL screen name (with any spaces removed -- "John Doe" becomes "JohnDoe" or "johndoe" -- this is what we call "normalizing" a Screen Name) and that Screen Name's AOL (not AIM) Password.
The SMTP server requires authentication in order to send mail through it. Just as with the IMAP server, log in using the normalized AOL Screen Name and its AOL Password. You do not need to use the AOL SMTP server, but your message will not appear in your AOL Sent Mail and may be blocked by filters that do not believe AOL members should be sending email without using the AOL SMTP server.
Access to these servers is available whether you are dialed into AOL or another provider, regardless of whether the AOL software is signed on. AOL members using hourly rate plans will not be charged for accessing these servers -- provided they're not dialed into AOL while doing it. Access to the servers will be listed as "<NetMail>" in the Detailed Bill.