"I lived with a Brazilian coach in his dingy apartment and trained every day," he says.
But he also found time to compile a kind of video diary (modelled on the still-photo blog Humans of New York) in which he "bailed up random Brazilians and asked them existential questions".
Artfully edited and with excellent music, the footage premiered in Being Roskill (you can find it on YouTube), an online documentary mini-series, as Christopher calls it. "Mini-documentary series" might be more apt, since the series is potentially endless and the episodes between 10 and 20 minutes long.
The first two series were a chronicle of the football team's "journey", he explains, but episodes one and two of series three, which went up in the past fortnight, make the link to Brazil, introducing us to two Brazilians whose lives are as different as may be imagined from those of the boys in Christopher's team.
Marcos Antonio Souza, 35, from Salvador, runs a football school in his neighbourhood they use waste ground or a beach; there are no fields as a way of distracting the local youngsters from the lure of drugs and street crime.
"It's not just about kicking a ball around," he tells the kids as they gather for a session. "It's about becoming a better man tomorrow."
Far to the south, Christopher met and filmed a 31-year-old called Sergio who lives where he grew up, in the Sao Bento favela in Santos, near Sao Paulo, the country's (and the Southern Hemisphere's) largest city. "Favela" are the urban slums in big cities which range from pitiful shanty towns to established neighbourhoods with their own complex sub-cultures and proud identities.
Sergio, who works as a receptionist in a budget hotel, talks of his hardships and joys; the importance of family; the value of a sense of humour as a life tool. Then, as a reminder that even the best documentary is a construction of reality and not reality itself, Christopher has edited in a sequence in which the Lewis twins and Mohamed ask questions to fit the answers. The result is a touching vignette of cross-cultural understanding that has plainly enlarged the worlds of everyone involved.
The enthusiastic Christopher, a third-year English teacher and the school's director of football, thinks his boys have learned from the experience.
"Sometimes we do sessions about topics that don't fit neatly into the curriculum what you might call life issues. I don't claim to have heaps of experience; I'm a young man myself. But I talk about my experiences of travelling and how I'm struck by our differences but also our similarities.
"There is a fundamental nature that binds people and I'm interested in asking those fundamental questions: just because Sergio is Brazilian and speaks Portuguese doesn't mean he's different. The boys see him and they see themselves in him."
Glen Lewis agrees: "It's good to see the perspective of someone on the other side of the world. We see what the hardships of life are like and what we have in common as well as the differences. And we see how much people care for football over there."
Football is the thread that connects them, of course. It's hard for anyone who hasn't been to South America (Brazil and Argentina in particular) to grasp the scale of the passion people have for the game there, which dwarfs All Black fever.
If there are to be tears this morning in Brazil, you may be sure they will be measured in gallons.
