Swapping out a tailcap boot is a frequent project for many flashlight owners. The process is not difficult, and requires minimum effort. Essentially, remove the tailcap and remove the retaining ring from the inside of the assembly. When the retaining ring comes out, each component of the tailcap will be accessible. Simply replace the old booth with your new one and then reverse the steps.
To make things easier for you, we've included this step-by-step video to walk you through the process.