Instant Messaging as SMS

Posted this question on Yahoo! Answers then realized I'd probably get more help here.

I recently bought an unlocked Palm Centro for use with T-Mobile. I have an unlimited text messaging plan and want to use AIM on the phone. The problem is, all the AIM clients I found use data. I do not want to be charged for data usage because I do not have a data plan. Are there any AIM Clients for Palm that use SMS to send messages instead of the internet?

Thanks in advance.

copied in your question...

The reason you can't find an AIM app that uses SMS is because SIM needs to transfer certain data over the internet that can't be done through SMS. The only way you'd get around this is to send sms messages to an aim e-mail address.

Well, I guess I'm stuck with using the AIM TXT service.
Thanks for responding.

the Palm Centro is better than your mom