Sorry, I made it (it seems)!
Lurking further on the net (here) I have been redirected to the right path:
After a new restart (init 6), I can finally see the plugin appearing:
Now, I just need to configure it 
For the benefit of other BH users, here is the full command:
root@192.168.1.47# cd /usr/lib/enigma2/python/Plugins/SystemPlugins && wget https://github.com/OpenViX/HRTunerProxy/archive/4.0.zip && unzip 4.0.zip && mv HRTunerProxy-4.0/plugin HRTunerProxy && chmod 755 HRTunerProxy && rm 4.0.zip && opkg update && opkg && opkg install python-argparse && init 6
Thanks MIky for the support!
