There's a plastic cover that pops off on the roof where the visor mounts. I think there's just one small screw under that cover, and it on a little plastic clip that slots into place. THe cover can be a pain to get off, just work at it with a trim tool.
The visor can be a pain to get back on too, since you have to slot that clip in just right to get it to line up.
Apart from that the entire visor is just one assembly.