I used a sitz bath a few days after my homebirth (to speed-heal a small tear that was flirting with infection) and used an herbal concoction prepared by my midwives (so I don't have the recipe to share, sorry.) After the herb stuff was used up, I used some sea salt (& kosher salt) to make some nice warm soothing saltwater.
I do wish I could've had my sitz bath up and running right away post-partum, because that would be a great way to pee during those first 24 hours post-partum! Peeing in the shower, in a bath, are great ways to ease the pee...but a sitz bath is speedier, because you're just filling that bowl on the toilet, and then you dump it into the toilet. I also love a peri-bottle sprayed on the perineum, but dunking one's whole bottom in water to pee sounds heavenly!
Ohh...and you could use a bit of cool water (instead of the ice pack to the perineum) too, I suppose! A 101 uses, to be sure....if you can withstand the embarassment of purchasing the sitz bath (I just sent my poor dad out to do that chore....but I was embarassed to ask him!)