You could use some software to remap those buttons. For example I have logitech mouse and I used Logitech app to remap additional mouse buttons to numpad. That allows me to map those buttons to any software that supports numpad buttons from keyboard. Check if your mouse supplier offers any software to remap them or try autohotkey for Windows.
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I don't want to be the oneThe battles always choose
'Cause inside I realize
That I'm the one confused