For Wii yes. Click Config and go to the Wii tab, then enable EURGB60 mode or whatever it is called (aka PAL60). I do not think it works with 25 FPS games though (or not every 25 FPS game).
Some GC games require you to hold the B button as they start up, and this should allow you to switch to 60Hz mode, but not all games support this.
Some GC games require you to hold the B button as they start up, and this should allow you to switch to 60Hz mode, but not all games support this.