I would do this outside of Premiere.
Though the web site information deals with NTSC, the script's author (Dan Isaacs) has built in several PAL options as well. I've just never used them.
Sorry but I think this is not usefull. I am not trying to do 24p or 25p.. I am trying to do 50p by merging the fields in an unconventional way (but that is standard for LCD TV sets that work at 100 Hz)
That may very well be possible using the method linked to. But I don't use PAL, so you will have to do the research yourself. The settings and what they do are included in the downloaded .zip file.
I guarantee that if it is possible, Dan's script will produce probably the best results you will find anywhere.
Ok.. I'll try.. still if you don't use pal it will be 60i to 60p.. same thing