When in doubt  don't do it
I tried and did a web look up but came up with only one thing  about mixing
coconut milk and fruit to feed to dogs in a emergency it was on a disaster
site http://www.drbasko.com/emergency.htm

Milk can be hard on a cats digestive system some can't tolerate it at all.
My Rumble thinks my bowl of cereal is his personal food dish and tries to
fish out the cereal when I eat it.

I am sure some one else will pop up with a answer

I use coconut oil on my skin sometimes and as soon as I open the jar,
my cat comes running.  She loves it.  I give her a few licks off my
finger.  If you do give this to your kitten, I would only give a very
small amount, like just a couple of sips.  You don't want to upset her
tummy.

I think coconut 'milk' would be safe, since as previously mentioned it's not
technically milk. After I was born, it was discovered that I couldn't
tolerate milk of any kind...breast milk, cow/goat/etc...no actual milk
worked for me. I lost 3lbs in a week(I wish I could do that now). Coconut
'milk' was discovered as the only thing I could tolerate. I always had a
fondness for the stuff, but it wasn't until a couple years when my mother
told me that when I finally understood why. I'm a weird person who tends to
like stuff that keeps me alive :-)  Anyways, granted my system isn't like a
cat's/dog's, but it's merely an example that coconut 'milk' is a viable
alternative to real milk.