Here is one quickly made arexx example for you. Edit the config line to be suitable for you.

You don't have to run ANR separately, just run this script from PolyOrganiser. Give wanted url as an option for it like this: rx anr-record.rexx http://sd-1634.dedibox.fr:8000/stream.mp3

Then you can also stop it with "stop" or "stopsaving" argument from that PolyOrga or whatever...