They don't need to enable it, it's enabled. Yes, you can put mutable data in the DHT used by all libtorrent programs (qBittorrent for instance).
For BEP 39, "Updating Torrents Via Feed URL", added torrents with `info.update-url` would hit a feed to check for updates. Does qBittorrent actually do this?
For BEP 46, "Updating Torrents Via DHT Mutable Items", qBitorrent would have to allow adding torrents via magnet link with `?xs=urn:btpk:PUBKEY`. I tried this, and it didn't work. Is there some other way to do this?