Are there reference implementations of ECQV implicit certificates?
For the sake of moving this question off of the "unanswered" list, the answer seems to be no. I spent time looking as implicit certificates are relevant to a project we are beginning to work on.

SECG, which has the draft standard for ECQV, does have a future project for test implementations of their standardized primitives/protocols.

They have a mailing list, but I have not subscribed. You could ask there.