If the phone supports third party application installation, then yes, there probably is availability for yahoo's IM chat. It's most likely not going to be from yahoo, but another developer, or free and open-community development.
Best thing to do is to locate a mobile applications website (there are tons of them out there!) and see if any of the IM programs that have yahoo connections supported work for your phone model.
For instance, on my Nokia E71 I'm using Slick messenger which was free to download and use. It mainly depends on your phone model.
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