Sorry to spam the mailing list, I just figured out my problem.
I was able to use the 'modutil' command to add my custom library into the nssdb at
/etc/pki/nssdb/. Then p11_child was able to locate and use the library to read my Smart
Perhaps there is a smarter way to do this via the update-ca-trust command, but I am OK
with just running modutil after installing our custom SmartCard library.