>>C<< Valve Spring Retainer Lock Installation
WARNING: This page is about a different car, the 2012 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.
In the same manner as removal, use special tool MD998772 with special tool MB992090 and special tool MB992089 attached to compress the valve spring, and install the valve spring retainer lock.
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.