I put Meprolights on mine, but installation should be the same for Trijicons. The front sight screws in from the bottom with a small hex nut, just like on Glocks. Make sure you put a drop of blue threadlocker Loctite on the threads before you tighten the hex nut. The rear sight will require just a bit of filing to get it to slide in with little or no resistance. It's necessary to have the rear sight be able to slide relatively freely through the dovetail to allow for adjustment. The rear sight is held in place not by friction like on most sights, but by the little spring-loaded split finger that fits into the bottom of the windage adjustment screw.
For what it's worth, I prefer the Meprolight brand over Trijicons for night sights. The dots are much easier to see in daylight. You can go to this link to get Meprolights for your Walther, and you can also click on "Installation Tools" to buy a Glock front sight hex tool. Trust me, it's better than trying to use something you buy at the local hardware store. The ones at the hardware store are usually too thick to properly fit into the tight space in the slide underneath the front sight. Arizona Gun Runners
Also if you need some files for the rear sight, you can find a set of miniature Nicholson files at Lowe's. These little files come in handy and are good for any gun owner to have.
Thanks for the reply BJG. I've already ordered Trijicon sights and they are on the way. Installation sounds easy from what you said. I do have gunsmithing files and I'm hoping Trijicon will include the little hex wrench. I'll post something about the sights and installation after I get done with it. Thanks again.
BJG, I received my Trijicon sights today and they went on easily. The rear sight just slid on like the Walther original. As for the front sight I made a little slit with a Dremel cutting disc on top of the hex nut so I could use a small screwdriver to make tightening easy. I also used Blue loctite as you suggested. Thanks.
The Trijicon rear just slid on with no fitting? That's nice. I wish the Meprolight was like that. Smart thinking on the front sight hex nut installation. The blue Loctite should keep it from coming loose. I used it on the Meprolights I installed on my Glock back in 1993, and the front sight is still on there tight after 12 years and thousands of rounds.