Sorry for my late reply.
First gen Tacoma (pre-2005) is completely different in terms of trim compared to the 2nd gen. If there's a grab handle on the A-pillar, it makes it easy, but not many of them have it from what i remember. No first gens have curtain airbags so that simplifies things.
Someone posted a pic of a white clip and said there's a release button on top. There is not a button on that kind of clip. You just need to pry those out of the body of the truck using a V-shaped tool, then slide the clip into the corresponding U-slot on the plastic trim cover. There are usually 2 or 3 of these clips in a typical Toyota A-pillar trim. To reinstall, just gently snap these clips back into the holes on the body. I'd take a photo of a similar trim clip on my car if I wasn't out of town right now.
As for the rubber weatherstrip on the body, it's very narrow on gen1 Tacoma compared to 2005+, and depending on which cab you have (single, extended, quad, and maybe whether it's a prerunner or not) it may not actually go over the edge of the headliner or dashboard (as pictured earlier) at all. They kept it simple on earlier trucks. Either way though, if you do pull the weatherstrip down off the body, take it slow. Toyota often used a really tacky black tar-type adhesive that stretches into thin threads and makes a heck of a mess. It's just about impossible to get out of the headliner or seats, and not easy to get off your hands either. Just take it slow and you'll be fine though.