BlackBerry Torch 9800 used Slide Style Qwerty Keyboard and Touch Screen for User Interface, but if you looking for Yahoo messenger for BlackBerry Torch you just need to explore deeper to your Torch Application Menu on Instant Messaging sections.
|Yahoo Messenger for Blackberry Torch 9800|
As long as we knew, the Client Mobile for Yahoo Messenger in your BB Torch is available by default (built in - if not it should be had a preinstalled). That why all you don't need to download the mobile client for ym.
Unless, you wanna used Multi Protocol IM Client to simplified the Application of IM Account because you do had many of Messenger Account such as ICQ, WLM, Yahoo and etc, you can used for example ebuddy for blackberry or xumii mobile client.
But, if you do want to install and download manually do to trouble error in your default Yahoo Messenger for Blackberry Torch, you can download it at here.