Set your console to PAL mode using, say, the enigmah video switchdisc. (if it isnt already)
Then head over to winuaex. You can set video mode to PAL in each game's config, but I think thats the default anyway.
Set the res to 720x576. You can set force PAL 50 mode in the video settings as well but it wont do much because you have set 720x576 already which is a 50hz screenmode. Enable show FPS and start a scroller like turrican 2 - it will hover around 50 in the top corner and be nice and smooth!!