Michael Brewer, 15, of Deerfield Beach, gave them a full account Monday.
He suffered second- and third-degree burns over two-thirds of his body and is listed in guarded condition in Jackson Memorial Hospital in Miami.
His mother, Valerie Brewer, told "Early Show" co-anchor Harry Smith Wednesday Michael is making progress in "leaps and bounds. (Tuesday) in physical therapy, they actually had him up, walking up and down the stairs."
Michael's physician, Dr. Nicholas Namias, the head of Jackson Memorial's burn center, says Michael "still has significant hurdles ahead. They're not dramatic hurdles every day, they're hard work hurdles for him, over the long haul. ... He has to go to physical therapy every day. And it hurts. Every motion, every movement, because his major joints really all are affected. Every motion that you and I take for granted hurts him."
More than $100,000 has been raised on Michael's behalf, and the family has gotten a massive outpouring of support. "(We came) very close to losing Michael," Valerie told Smith. "We are eternally grateful for all of the prayers and cards and letters that we have gotten from everybody. ... It's incredible. It's not just (our) community, it's the world. We're receiving letters and cards from as far away as Russia. It's really incredible. It's restored my faith in humanity. It's helped us to get through our daily achievements with Michael."
Police say a dispute over $40 led to Brewer being doused with rubbing alcohol, then set ablaze.
The youngest of the alleged perpetrators, Jeremy Jarvis, 13, spoke to the media Tuesday, apologizing for his role in the incident.
"I want to express my deepest sympathy for Mikey and his family," Jarvis said, reading from a prepared statement in front of his lawyer's office. "I will pray for Mikey to grow stronger every day and for Mikey's speedy recovery."
Jarvis asserted that the attack wasn't premeditated.
Though he's not charged with a crime, Jarvis and another teen are said to have stood by as the others carried out the fiery attack. The others face charges carrying a maximum of 30 years in prison if convicted, authorities say.
One of the accused is Jarvis' older brother. His former schoolmates have been charged as adults with attempted murder and could face 30 years behind bars.