This page describes the process of adding an IR filter right in front of the sensor of the camera. I prefer this option than attaching a filter to the lens because all lenses have different sizes and it becomes a pain to find the right filter. But if you are committed to a particular lens. You may want to just add the filter on the outside.

Order IR pass filter. I’ve had luck with this one from edmunds.

Then, cut it into 14x14mm pieces. Score it with a knife multiple times and then carefully snap it with pliers while holding it with a soft tissue in between. I use lens cleaning wipes.

Then remove the two screws holding the “ring”. Remove it and then remove the glass. Replace with the new glass quickly, don’t let dust go in. And screw it back together. Don’t need to get it perfect before screwing it. While screwing it, it will usually go into place.