I have a CMVS I wired a DIN like that (AES pinout with left audio on the composite video pin) but I just never got around to ordering a custom cable for it. retrogamingcables.co.uk used to be great with custom orders. Maybe they still are.
I too am curious where to tap line level stereo from on an AES. You'd think somewhere after the DAC(s) before the headphone amp would work, but maybe an extra amp board would be needed, like with some MVS boards.