Thanks guys!
I figured it out eventually.
For anyone else who happens to stumble upon this post: look for function modules: CHANGEDOCUMENT_READ_HEADERS for information regarding user/date/time/tcode and CHANGEDOCUMENT_READ_POSITIONS for old/new values (where TABLEKEY, in this case, is a concatenation of SY-MANDT & EBELN & EBELP.
Regards,
Tudor