Dub Greedo in English but include subtitles for him anyway (either English or Rodian/Huttese/whatever language he speaks in the original film).
Better (worse): use the original on-set English dialogue (which is from the script before the Jabba scene was cut and the Greedo scene dialogue rewritten to convey the now-deleted exposition), but keep the theatrical subtitles.
I like the idea of having the subtitles in the same language as the audio but saying different things. Funny enough, I’ve actually seen that happen before when watching a film in a non-native language.