Well, it's bit same thing like Methu did; he needed base vampire template first before taking vampire lord template. You need template which turns your base creature (Korachon) into ooze creature or count as ooze. Then you can take sentry ooze which improves the 'base' creature. Then in end you cease all subtypes and counts just as outsider subtype wise unless take special quality to count as ooze as well (albeit sentient one).