It can be done, there is a BB app and a computer programme which allow you to BBM from your computer but it is in essence just remote control of your Blackberry phone rather than a dedicated BBM client for your PC.
The link above will give you what you need to BBM from your computer
u can use an app. that i used to use ,, its perfect to control ur bb throw ur pc, its name is SOTI pocket controller-pro ,, install it on ur pc and ur BB then chat and do all the controls throw ur pc,, its a fee app..
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