parse the talk page - probably error-prone, only reasonably well formatted sections/posts would be safely recognized
parse the diff obtained from recent changes
The second way also identifies the responsible editor, so it could be immediately marked with the Template:Unsigned, but the first method would identify even old posts (or at least some of them).
This could be done in two ways:
The second way also identifies the responsible editor, so it could be immediately marked with the Template:Unsigned, but the first method would identify even old posts (or at least some of them).