This is not a native function in BlackBerry. It will probably not going to be one in future either because of the security concerns.
Originally Posted by visavon
3rd party apps like NFCShortcuts + ShortcutMe can do a lot of things because you can write macro for almost anything.
However even those apps don't work in this case, because when the BB is locked, the BB OS turns off the NFC mode that reads tags. So no tag reading when the device is locked, therefore no auto log in with NFC tags.