It depends on what I2S chip you are using, 'popular' chips like the WM8804 or UDA1380 have linux kernel drivers already. In theory you could just hook up the i2s IC/circuit and then load the kernel module (after you compile it) and start using your i2s sound card.
Are you designing a board for the Edison? Or are you just 'experimenting' right now? if you are just tinkering, you could get an 'already built' i2s audio module from DX or ebay to try things out.