Just listened to a few Finns pronounce it and the closest seems to be Her-pee-a, though the "her" part is a bit, well, more Scandinavian, than we'd pronounce "her"
Poyet is pronounced Poo-shet in Uruguay apparently, never heard anyone say it like that though. I dont hear anyone calling Jones, Jowens like they do in Wales, so I shall be sticking with Hippier for Hyypia. Unless Aspinall comes up with something I like better.