Help with Training Programme..... 55km walk....

Chezza021

I am wanting to take on Hump the Stump. It is a 55km walk over a 24hr period. Starting at midnight. I have a pretty good walking fitness but 10km of the track involves a pretty intense hill climb from sea level to 1000m. This is the link for the challenge.

http://www.humpridgetrack.co.nz/index.php?pageLoad=157

Any tips for training would be appreciated... I am not a runner yet an this would be my first HUGE achievement.