I heard three pronunciations of "Wacom" yesterday and I'm still not sure if there's an official one and if so, which it is (if it's not a fourth).
* - while the ワコム part is not ambiguous, you can technically choose to pronounce the rest of the word (株式会社) differently - since these characters have multiple pronunciations - though choosing to do that would be considered a very strange thing to do in this context, since its otherwise got a standard pronunciation.