you should filter the connection with iptabels or whatever software is available for doing that.
There is no way to do that and, in fact, it is non-sense since the defautl *nix way is to accept first the /etc/ files and, if availbale in ~/, ignore the /etc file and use only hte one in the home (~/) dir, so any user would still get whatever upload rate they wished.
I can only suggest you to configure properly the bandwidth each user is allowed to use in your network with proper software.
Greets!
