Despite their own personal trials, Maddox's parents vowed to help all other families who suffered from the disease by raising $1 million to go towards equipment, resources, training and support for families affected with by the disease.
So far they have raised $124,409 for the cause.
Team leader and Tauranga firefighter Kevin Cowper said they would try to tackle the walk about February 21 but it was weather and full-moon dependent.
"As soon as the weather looks good for a couple of days, bang we will be gone. We have a five-day window where we will be able to go."
Mr Cowper said they would start the walk at midnight and hope to have it completed within 24 hours with about a four-hour drive from Taranaki to Ruapehu in between.
Mr Cowper did "a bit of training" across the weekend and scaled both Taranaki and Ruapehu in one day.
"That was hard enough, put Ngauruhoe and Tongariro on after that, it will be a big long day."
Mr Cowper estimated it would take the group about three hours to get to the top of each peak and a little less to get down. The pain would be worth it though, he said.
"We are all firefighters and we all look after each other at work. In hard times you help out. It's not about us, it's about John and Rebecca. I wanted to do something for the cause.
"It's not just about raising money either, it's also about raising awareness. One of the things they found when young Maddox was diagnosed was there was hardly any information about it, so it's about raising awareness too."
-To donate to the cause visit www.fundraiseonline.co.nz/MitochondrialDisease/.