I'd like to modify certain Gamesettings e.g. fSneakMaxDistance by acquiring a normal perk, however I haven't been able to figure out how to do so.
Any suggestions on how to do this?

Bump~

Unfortunately, there are not "SetGameSetting" functions in Papyrus. I think you'll have to wait for SKSE to implement this one.

Cipscis

Alright, I've got one more question though and it'd be a waste to make another thread for it.
I was wondering if it's possible to modify the Movement type settings (like NPC_Sneaking_MT) by attaching a papyrus script to a perk.

However, there is the http://www.creationkit.com/SetINIFloat_-_Utility function. But I can't get it to work.

Could you post an example of how you're trying to use it? Does your script compile correctly? What happens when the command is supposed to run - nothing at all? Have you made sure your code is running with a debug command of some sort?

Cipscis