I hear that.
To clarify for anyone else coming across the thread who might wish to try it- The internal mics almost certainly use a 2-wire connection, so once opened up it should be simple to splice in a stereo mini-jack.
Caveats are:
It's strictly an unbalanced mic-level input with PIP voltage on it. If there is no menu or hardware switch to turn off PIP (I assume not) and you aren't using mics that operate on PIP, you should include blocking capacitors as would be used in a battery box, except oriented the opposite way so as to block the DC bias voltage coming out of the recorder rather than being fed into it.