if you don't have the program go to
http://www.havit.hk/support/downloads/
download the driver and install, should open up the program for your mouse
in the program you should go to mouse keybinds
by default they are set to OFF for whatever reason, go ahead and set up the keybindings to your liking but in order to work and make sure you set them up how you want it in Arma and TS