He will ride as the Reverend Samuel Marsden, the Anglican cleric and missionary who is generally acknowledged as introducing both Christianity and the horse to New Zealand.
New Zealand's first horse came ashore with Rev Marsden in the Bay of Islands on Christmas Eve, 1814
Locals who had not seen horses before believed at the moment that he was more than mortal, the organisers of The Mane Event said.
For Dean Rickman, the event holds a special place in his heart as he grew up around horses - but never had the opportunity to ride them.
"The futility of sending horses into war like that is horrific. The calvary charges into machine guns. It is just a real loss of life," Dean Rickman said.
He is humbled that he will play the role of Rev Marsden, who conducted the first Christian service on New Zealand soil during Christmas Day 1814.
"He was an interesting character and a man not without controversy. He had some dashes of colours in his life and was a significant person in New Zealand history."
Dean Rickman has been taking riding lessons with Noeline Jeffries, one of the organisers of The Mane Event, at the Waikato Equestrian Centre.
"He had a period of three weeks off where he was a little rusty but he's just picked everything straight back up," Ms Jeffries said.
"He is a pleasure to teach and has natural talent. I can't believe how quickly he's progressed.
"He wants to carry on after the event as well. He's so proud."
Ms Jeffries said that preparation for the event has been coming along well and that the only concern was that he would be riding a different horse on the day. Dean Rickman has been learning on an Irish draught horse called Tara, however Tara will be unavailable.
As well as the Marsden re-enactment The Mane Event will feature jousting, dressage, pony rides and more.