Great, thanks! I put the files from the guide I linked to in the correct place but then the 3dsx version of the SafeA9LHInstaller wouldn't work (hung on black screen), presumably because I'm using updated sysnand. So I replaced my arm9loaderhax.bin file with the SafeA9LHInstaller one, booted, got to the installer, and updated my a9lh. Then when I put the latest AuReiNand a9lh bin file on the SD card I got the new config menu and was then able to boot back to my sysnand through a9lh
Long story short - I think I'm now on the latest a9lh so I'm going to try BootAnim9 again
Edit - update: yep it worked
Thanks guys!