Adding Frame Interpolation & Forcing 120hz+ on emulators like Dolphin

I was looking to add frame interpolation & to force the framerate on my emulators (particularly Dolphin & Primehack which uses Dolphin as a base), but I can’t find any good instructions on how to do so. I was able to do the same with Tekken with the Tekken overlay. Is it possible to do this, because when I have looked online, it says it is possible.

The only information that I saw to force 120 fps was to replace the .ini file in the Special K profile, but when I deleted the file and replaced it with another .ini file, it just ignored it and reloaded an .ini file.

Also, when I utilize Special K with said emulators, It wont allow my controller to be read in the emulator.