Here you go. Nano 1G PL3 for FW3.15 using a fresh clone of the PL3 repo.
Now keep in mind that with the PL3 payload the timing on when you start rockbox and when you hit power/eject is very critical. My advice is start rockbox and immediately hit power/eject. You might want to try a few different time intervals to get it going. Once you work the sequence out it'll be easy.