ok, this is what my reflexologist advised and what i did:
buy some sea salt, put generous handful in the bath, and fill the bath to just a few inches high. its a sitz bath you want, she told me this is not a relaxing bath! then (sorry if this is tmi) open your legs and 'sloosh' the water into the wound with your hand. if you lie in the bath normally, your legs are actually closed and the salt doesn't get to the wound. i did this for 5-10 minutes as many times a day i could (usually 1-3).
i was examining the wound daily so had a fairly good grasp of how it was healing. and after a few days i could see the wound was healing quicker when i did this.
just to be clear, its still going to take weeks/months to heal. but i did notice a difference in the rate of healing.
also other caveats in what i'm saying are that in the medical literature as i understand it there is no conclusive evidence that salt baths work. i'm just describing my experience. and my reflexologist suggested salt baths to me after speaking to a mw and a senior mw on my behalf.
also, some people find salt baths sting (which is why i didn't do them in the first few weeks as i had heard this). for me it was fine so i carried on, but i did find if i didn't wash off the salt after the bath then it did sting, so i guess you can control this by adjusting the level of salt, or how long you're in the bath.
the other thing to emphasise is airing the wound. this was the thing that made the biggest difference. i didn't wear undies or bottoms in the house for about 3 months
lucky it was summer when i had ds but i guess you could just put the heating on!
hope this helps. x