Replacing the lift gate weatherstripping is pretty easy. First, I removed the old weatherstripping slowly while cleaning the edge where it's mounted. There was a bit of rust on the bottom edge, so I taped it off to spray a bit of rust reformer on it:
After that set up, I smeared some of the Toyota rubber grease all around the rim and started to install the new weatherstrip. First of all, there is a seam in the strip that goes in the middle of the bottom edge.
Center that seam with the lift gate latch. To make sure you have it oriented correctly, there are three orange marks and one white mark on the strip. The three orange marks go in the bottom corners and the top driver side corner.
This white mark goes in the top passenger side corner of the lift gate opening:
Use that mark and the seam at the bottom middle to make sure you have it oriented properly. It goes on pretty easily.
NOTE: I did not use any kind of weatherstripping or gasket adhesive. But I'm reading a few more threads and thinking that I should. I'll probably order some from Amazon.