When I got this phone, it took me two days trying to figure out how I can use it for yahoo messenger without paying for a data plan. First I downloaded opera mini 5 beta on my computer and then load it in my mobile. This thing is like a browser and you can access yahoo mail as well as the messenger there for free, the only thing is that when your log-in, your messenger status would be I’m mobile with the little mobile icon beside it. You will then refresh it periodically to check for new messages. Also you have to make sure that your connection preference is wifi only, you can do this by doing this procedure: first go to set up, then options, then look for mobile options, once you are in mobile option, you can see the mobile preference and set it to wifi only. Once you have done that part, go back to opera mini, go to yahoo website, and log in to your messenger. Just always remember to use wifi only on your connection preference so you will not be charge by your mobile network for internet usage.
If you dont want to get a mobile icon and a Im sms message on your messenger when you sign in to yahoo messenger on your phone you may also want to read my other post on using messenger on a wifi phone, this will enable you to log into yahoo messenger without downloading it.