Du Toit got on a bike for the first time on Thursday since she lost her leg in 2001, in preparation for Sunday's race.
She will form part of the SA Institute for Drug-Free Sport's (SAIDS) Play Fair team.
Du Toit used to ride as a teenager but stopped when she lost her leg in a motorcycle accident.
Khalid Galant, the SAIDS CEO, said Du Toit would take part in the race with a prosthetic leg.
"She intends going the distance with the team to help spread the message of drug-free sport through cycling," Galant said.
The SAIDS team includes national football coach Gordon Igesund, former Bafana Bafana defender Mark Fish, freediving champion Hanli Prinsloo, motorsport champion Gugu Zulu and Gauteng transport MEC Ismail Vadi.