A number of online stock trading options are available to invest in Karachi Stock Exchange (KSE) these days. While AKD Trade might be the best service in this regard, it requires a deposit of Rs. 200K. If you would like to start with a less demanding provider, ClikTrade.com might be a good fit, albeit with low quality of service. You can open up an account with Rs. 50K.
An interesting related site is Virtual KSE, modeled after FOREX.com; it lets you virtually trade in KSE for free!