I'm sorry, but I really can't say. If the hardware is the same as the Cybook or the STAReBook, then your chances are quite good, if it's a newer and/or different hardware then you're out of luck. I don't know much about the Astak Mentor, from the picture I just found it looks like the STAReBOOK, so it might just work.
Use at your own risk though...
I'm not sure if the files are even still out there though...if you can't find them on the net then send a PN and I'll search my archives, can't promis I still have it though...^^