rwm
exec player
# Control^C took me to Shell Exit so I had to use another Control^C to kill it again, and do:
rom
exit
[...]
My next thing to try is timing on the Control^C - does it make a difference if I do it while the Loading Playlists message is up?
Yes. You need to wait for each stage to finish before doing the next one. So at the shell prompt, type rwm, hit return, and don't do anything else until the next shell prompt "#" appears (this takes a while on big disks).
Then exec the player, and don't do anything else until everything has finished building and the normal player screen appears.
Then hit q, or Ctrl-C, and once the "#" appears issue the rom command.
Peter