These are all of the policies I set up for software restriction. I wasn't too successful blocking all installs, sometimes it would work, other times it wouldn't. 

1.) Turn Off Windows Installer: Prevent users from installing software on their systems or permit users to install only those programs offered by a system administrator. 
Path: Computer Configuration> Polices> Administrative Templates> Windows Components> Windows Installer> Turn Off Windows Installer. 

2.) Don't Run Specified Windows Application: If you enable this policy setting, users cannot run programs that you add to the list of disallowed applications. 
Path: User Configuration> Policies> Administrative Templates> System> Don't Run Specified Windows Application.

3.) Detect Application Installations and Prompt For Elevation: When an application installation package is detected that requires elevation of privilege, the user is prompted to enter an administrative user name and password. 
Path: Computer Configuration> Polices> Security Settings> Local Policies> Security Options> User Account Control> Detect Application Installations and Prompt For Elevation.

4.) Always Install With Elevated Privileges: This policy setting directs Windows Installer to use elevated permissions when it installs any program on the system.
 Path: User Configuration> Policies> Administrative Templates> Windows Components> Windows Installer> Always Install With Elevated Privileges.