I've been thinking about this as well. I'd personally roll a multi-classed Alchemist/Magus and possibly use the Words of Power sytem for the Magus spells to better simulate the Signs from Witcher (whilst leaving the alchemist spells as they are).
I also wouldn't worry about the race so much (it;s mostly cosmetic+potions in the game anyway) though you could take the internal alchemist archetype to get the cool meditation thing going.
