I didn't build the new ROM for myself yet as i am not using any Docker stuff and don't even know why i would need it (please don't tell me).
I am sure the ordinary 'bsdiff' method could be applied from any Amiga using spatch or similar.
The Ext (Boot) ROM of the CDTV is small enough to even create a bootable floppy disk doing the whole Rip&Convert in one go.
Patching a 256kB binary blob should be easy to do without installing, like, a full application.