GPS/English stereo upgrade for Toyota Corolla Runx

Hi, recently bought a 2002 Toyota Corolla Runx (same as the 2003/2004 models) where the stereo system, with screen, has a GPS navigation system included.
Unfortunately its all in Japanese, and I was wondering if anyone knows if its possible to get NZ maps installed on these, or get an NZ maps dvd so I can use it in the DVD drive.

Anyone else had any luck with these! Seems a shame to remove and put in a new stereo when this one works well.

Thanks

This is a question that would be good if you could do a sticky at the top of the message board

I bought the 2005 runx model with exactly problem. dont know how to make it works....does anybody know something about it as all in japanese, cheers