Hmm... would it be a case of changing the OpenBor file that comes with the Golden Axe Myth zip, seeing as it runs durectly from that? So you'd adapt the .exe into a gpe/pnd and run the whole thing as a whole (rather than an extention of the original OpenBor pnd we have)?
EDIT:
Okay, did a bit of digging - there was an OpenBor V3.0 released for PSP with SPK support (didnt support PAK), so that would be what we need. Some sort of conversion of a more recent OpenBor (3.0 or higher) would do the trick and should run this fine.
Now we just need someone to PND OpenBor V3.0 (or at least at SPK support to the current build)...