Creating a SPKAC

I just recently tested the KEYGEN element on firefox and it seems to be
working fine.

However I'm unable to validate or sign a SPKAC [1]

Does anyone have some code to do this?

openssl -ca -spkac ./test.spkac

Should verify the certificate signing request.  But I've yet to find a file
that verifies.

Anyone got one?

[1] https://en.wikipedia.org/wiki/SPKAC