I just buy cheesecloth from Walmart in the crafts section. Cut a small length, fold it over itself and twist into a wick, then coil, install, and fire when wet. Works just fine for me, but I haven't had a chance to try it on the T3 specifically yet as I'm still working on the original coils. So far I'm loving the T3, but I wish I could get just a little VTF out of it, so here's hoping my cheesecloth does the trick when I'm ready to rewick.
The packaging indicates uses for cooking and baking as well as for crafts and household cleaning, so I don't see much need to boil it. Everyone has a different opinion on the safety of these products straight from the packaging, though, so always use your best judgement when rewicking with cotton, bamboo, or hemp products.
I lost all my old flavor wicks (the loose wicks) while cleaning my coils. I figured it didn't matter much anyways since some people recommend removing them. They were fine for a while, but now a lot of flooding, gurgling and leaking so I think I may want to replace the loose wicks on mine as well. I think you could get by with just cleaning them when you clean the coils, since you have to remove them in order to see the coil well and by then it's probably too hard to put back in if they're wet or stringy or start coming apart.
I guess cotton wicks from Walmart or whatever should work? Do I find these in the sewing or candle section...?