[quote:1rfgb9tj]So, it seems you need an actual Mac to upload a C2 Mac build on Steam, because of some permissions problems on the .app.
That's such a stupid requirement.
Then again, that sounds like Steam (and Apple for that matter). Could you pick up a mini and sell it when you're done with it?
option D: Virtualbox
Unfortunately, this isn't 100% straight-forward (okay, or legal), but it is certainly possible. Google "Niresh" and "MacBreaker". Honestly, though, I'd be wary of this option unless you have no other choice.
option E:
Anybody you know? Anybody on the forums you'd trust who has a mac?
Hope you are able to sort this out.