[KyleGoetz]

Originally Posted by Jorg

Why is "と" the correct particle?

I think of と as the "quotation" particle.
〜と書く = "to write 〜"
〜と読む = "to read ~"
〜と言う = "to say ~"
〜と呼ぶ = "to call/term ~"
etc.

And can ほしい always be used with verbs? I thought it was only for nouns and maybe adjectives.

〜てほしい means "to want someone to do something"
Have a look at examples: “てほしい”の検索結果（1285 件）：英辞郎 on the WEB：スペースアルク

Also, because you didn't specify "you" and "me", couldn't it be read as "What do I want to say?" For reference, how would you say the same sentence with "you" and "me" included?

No. "What do I want to say" is, first of all, a really weird thing in English, so it's hard to imagine how to translate it. Personally, the only time I'd use that phrase in English would be if I were speaking, then stopped to ask myself "what exactly ought I say right now?" In that case, なんと言ったらいいのかなぁ〜 or something. But this does not mean "What do I want to say?"

It's hard to answer this question because translation is about converting what is intended in one language to another, not about turning one word into another. If someone says "Honey, can you do this?" You don't translate honey into the Japanese word for bee vomit even though that is what the "honey" means, literally, in the English sentence (you're calling your spouse a sweet-tasting food). Instead, you might say あなた in Japanese, which just means "you," but can carry a connotation of lovingness between spouses. Something like "Dear" or "Honey."

With "you" and "me" included, it would probably sound like bad, unnatural Japanese. 〜さんは私がなんと言ってほしいですか。 Literally, it's something like "As for [you, Mister ~], you want me saying what?"