This is what I found from yahoo kefir group, but I haven’t tried it yet.
“I use my milk kefir grain with Thai kitchen coconut milk, and in about 24hr have a wonderful coconut-kefir product. I always return the grains to dairy after using coconut
milk, as they need lactose to survive.”
You can do 24hr fermentation, then strain the kefir, and then let the coconut milk kefir (without grains) sit in the kitchen in an air-tight bottle for another 24 hr.