Backup of Hond Sat Nav DVD?

[mobad]

Any ideas how this can be performed?
I remember reading in a forum you need DVD decrryptor, A dual layer DVD +r and a dvd rewriter that allows the changing of booktype to a dvd rom?

If any one knows the correct method, pls could you let me know.
Cheers

 

[blockit]

some get this method working on there alpines but I did not with + and- dl discs verbatin please let me know if you suceed