I haven't tested this in other than in Mavericks but it will "hopefully" will also work on Yosemite.

I've tested this on Mavericks, and it should also work on Yosemite. It wasn’t the easiest process, and while this may not be the perfect solution, it’s a practical one. If you’d rather not spend too much time on this, feel free to try my solution—just download the tar file from:

nss_macosx_10.9.4.tar.gz

Source code: nss-3.12.9-with-nspr-4.8.7.tar.gz

Untar the file at /bin so you should have a /bin/nss directory containing all the binaries along with libraries.

Update your environmental variables .. for the test you can do:

export PATH=$PATH:/bin/nss/

and execute

pk12util
Usage: pk12util -i importfile [-d certdir] [-P dbprefix] [-h tokenname]
[-k slotpwfile | -K slotpw] [-w p12filepwfile | -W p12filepw]
[-v]
Usage: pk12util -l listfile [-d certdir] [-P dbprefix] [-h tokenname]
[-k slotpwfile | -K slotpw] [-w p12filepwfile | -W p12filepw]
[-v]
Usage: pk12util -o exportfile -n certname [-d certdir] [-P dbprefix]
[-c key_cipher] [-C cert_cipher]
[-m | --key_len keyLen] [--cert_key_len certKeyLen] [-v]
[-k slotpwfile | -K slotpw]
[-w p12filepwfile | -W p12filefilepw]

If you receive something similar to the above, that means it's working as expected!
So go ahead, update the environmental variables for your applications.