That would be the CTMLoader, made by Zerradeth for the Flames of Eternity hack.
I emailed him long ago about making one for FFVI, relatively easily hopefully, since they share a similar music engine and SPC commands and all that, but in his own words:
"Okay, after some quick investigation, while the music formats for the game are the same, the engine itself is different. I'm not sure how different, but it at least uses different command numbers and obviously different offsets for sending information to the SPC. It would require a good chunk of rewriting and the behaviors that CTM mimics to "emulate" CT's audio engine might not be the same as those in FFVI."
I'm sure it's entirely possible though for someone who knows how to go about it, using CTM as a source - he seemed to be okay with that actually.