This guide is inspired by Prasys’ guide and ori0’s solution posted in comments. I didn't include BIOS photos in this post, but you can refer to the previously posted guide for general BIOS settings. Therefore, it can be much more complicated- you may run into trouble if this is your first attempt. Also, you will have to compile your own DSDT.aml, at least to stop the system from resetting your CMOS at each restart.
However, this guide does not enable sound or ethernet by default. It also loads the system directly without using any booted installer. It is more generic, and not system-specific, meaning you can use this guide for any PC that can run the Vanilla 10.6.2 kernel. Here is a second guide to install OS X on your computer using the Snow Leopard Retail DVD. NOTE: This guide is not current anymore: iBoot + MultiBeast is the recommended method for installation.