Heya,

From what i understand is that's not possible.
What you can do is the following :

Go in to Setup and look at Mouse-map.
From here you can add bindings so if you click Mousebutton 4 you can add whatever key you like.
On your alts bind the key you used and it works
Example you click mousebutton 4 and you have bind it with button [ it will click [ for your alts and just mousebutton4 for your main.

Hope this helps.
Regards,

Lyrix