I think i improvised the 1st time and used some thin metal coat hanger wire bent to suit.... after all you're just trying to release the plastic lugs...
Good luck. I've been looking at the same head unit, but i'm not quite how i feel about the non-removal aspect of it. I've had a couple of pioneer head units, the latest is a good few years old now, but has a nice feature where it balances the sound out to suit the position of the main listener (me in the driver seat) and adjusts all the speaker volumes accordingly... Also how many apps does this unit now have/control?
Post pictures when done please?