You want something like Wine for OSX programs. Sadly I dont think such a program exists, or if its even possible to emulate a space in which a single OSX program could run inside Windows.

You could obviously buy a Mac, but im assuming you are not made of money. Other than that there are essentially two other options; build a hackintosh, which is basically installing OSX on PC hardware. Or run OSX as a virtual machine inside Windows.

I didnt realise the latter was possible untill a few days ago I read an article about it from Lifehacker. The link below is from the article to a website whith instructions on how to setup OSX to run on Windows as a Virtual Machine.

Obviously, you need a legal copy of OSX to do this and as others have mentioned, its a grey area legal wise but I dont think you will run into any trouble with Apple. You will also need a copy of VMWARE 7. I did read you dont want to use this but its the simplest way of doing what you are trying to achieve. Its certainly easier than building a hackintosh.

http://www.ihackintosh.com/2009/12/install-snow-leopard-in-vmware-7-windows-edition/

Good Luck with your project :)