I think the problem is caused by two udev rules:
KERNEL=="mouse*|mice|event*", NAME="input/%k", MODE="0640"
I won't pretend to understand writing new udev rules and I've hacked only a few on my own. Do know that you want to add your own udev rule in /etc/udev/rules.d
and not in /lib/udev/rules.d.
Perhaps that is sufficient information to help you get started, but I'm sure somebody here will help you write a new rule.