Hi Jami,
I can't find anything either. What you could do, though, is contact dharma trading company [Tel: (800) 542-5227 Toll-free from anywhere in the USA & Canada]. I've ordered dyeable items and fabric paints from them before. They don't seem to carry sneakers, but they might know who does or be able to tell you how to remove the coating from the sneakers that causes them not to take dye. Any fabric needs to be pre-washed before dyeing, but if the coating won't come off in the wash, then it will prevent the dye from penetrating the fabric.
Sarah
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