This option is not included in BO2, in BO2 it is hardware accelerated, which in turn is defaulted by Windows.
To disable mouse acceleration, go to Control Panel/Mouse/Pointer Options and uncheck the option that says "Improve Pointer Precision"
Make sure he forwards 27016 to 27020, which is a good safe range to use. When trying to connect try using any of those ports within that range to connect. And make sure you're using their correct external IPV4 address, which can be obtained by your friend by them Googling "What is my IP".
