Hi,
after reading your post again it occured to me you were talking about the buttons
I always forget about.
To be sure everything worked correct I downloaded and installed the latest setpoint.
I was behind on this. I also checked the config in setpoint. In Windows the buttons
worked fine. Ingame (different games) however not, whatever setting I used.
So in setpoint I changed button 5/6 and configured them as keystroke assigned using R and J (choosen randomly)
as test. Ingame I now was able to trigger reload and chat with the left/right option of the scroll button.
Unless there is another way, it seems you need to find unused keyboard buttons, assign them to
those buttons and assign the keyboard buttons ingame.
In setpoint you can also set these options to specific programs instead of standard but I have not tried
that out yet.
You can find instruction here: http://superuser.com/questions/341820/logitech-g5-side-button-is-not-generic
It shows a MX1100 and program specific settings but the basics and config of the buttons are the same.
Be alert iof the button numbers though.
I hope this helps a little.