I don't think the launcher fully supports it yet, it seems to be broken. I also get a weird update loop that I can't solve when I add nampower in the launcher, so I guess that has to be done manually as well.
If you have it all installed, the way to launch the game with SuperWoW is to add the line "SuperWoWhook.dll" to your dlls.txt file in the main game folder, then launch the game with VanillaFixes.exe. It will then automatically load the SuperWoW dll, and prompt you about it when you open the game.
I think we need to wait some time for the launcher to be fixed. It also took Turtle quite a while to get it to work properly.
If you still have issues, there's a neat guide that you can follow step by step;
https://github.com/pepopo978/SuperwowInstallation