Okay, I got to try the Luigi's Mansion thing.
Forcing the game at PAL60 doesnt work, and forcing Progressive Scan through Nintendont launcher will create some weird input lag.
I tried with the code but it didn't make any difference... Until I saw that the code I created was empty except for some values the program forces when it's created (Is there any GCT editor that is not Smash Bros related? Kind of annoying actually).
Anyway, I redid the GCT file with the code (Version 2 of Hz option only) I quoted earlier and... It actually works!
A question in the Main Title Screen will pop up in english (Even if you have the game set to another one) asking if you want to change into Progressive Scan mode, if you say Yes it will change mode and enter into the File Select screen.
This brings the question : WHY in the F*%$ would Nintendo hide the HZ selector in the first case? It's an OPTION for god's sake...
So thanks to that code we can play the pal version (The best version Content-wise) without gimped speed forced by the 50hz. You can even activate the Widescreen option in Nintendont, although I rather leave it as it was originally.
I hope this information is useful for anyone.