You will access version 5.8 by winscp the folder /usr/lib/libretro and extract the file glupen64_libretro.so.
Now in version 5.9, it will access by putty and execute the following commands:
mount -o remount,rw /
mount -o remount,rw /boot
Access version 5.9 by winscp and copy the file to the same folder that you extracted from version 5.8.
Finally go to /recalbox/share/system/.emulationstation folder and edit the es_system.cfg file. On the Nintendo 64 emulators part add the following entry:
</emulator>
<emulator name="libretro">
<cores>
<core>glupen64</core>
</cores>
</emulator>
Back to putty, run the following command:
/recalbox/scripts/recalbox-save-overlay.sh
Done!
