I want to edit the /etc/sudoers file so that a non-admin user can install software via the Software Center in Linux Mint 10. The reason for this is that I want a user to have the capability to install programs, but not make any other configuration changes to the system.

So far I have the following (some of these may not make sense, I was just trying whatever I thought of)

username ALL= /usr/bin/aptitude 
username ALL= /usr/bin/dpkg 
username ALL= /usr/local/bin/apt-get 
username ALL= /usr/lib/linuxmint/mintUpdate/mintUpdate.py
username ALL= /usr/bin/software-center
username ALL= /usr/bin/synaptic

So far, it allows me to do updates without asking for my password, but it will not let me install software without entering an admin password.

I am aware of this question, How can I set the Software Center to install software for non-root users?, but this goes the route of modifying the PolicyKit, whereas I'm interested in a sudo solution, because it seems a simpler way to go.