The double amputee denied murder by claiming that he mistook Steenkamp for an intruder when he fired four gunshots through a toilet door at his home in South Africa in the early hours of Valentine's Day last year.
"He will write his own book," Van Zyl told the Observer. "We've discussed it. We've talked about ideas and concepts. I'm not going to go into details now."
Pistorius will be sentenced on October 13 and is expected to receive a custodial punishment.