No, you misunderstood...
Start game with my script (double click .exe or .ahk file if you have
AutoHotkey installed).
Now the Berserk Mode is still disabled.
Start new game with Commando. Press F5. My script can't interact with the game but only with the keyboard, so it doesn't know that you have choosen Commando perk.
Now button are inverted. Change weapon with "2" or "3" and you are ok. From now, only when you press "1" to equip melee weapon (not male ) the script invert your mouse buttons.
If you start with Berserker you don't need to "synchronize" your weapon, because you start with the crovel.
Try for yourself .