The correct answer to this open question is the following.
If I were going to run an Indian boarding school like the Carlisle Indian School, what I would do to convince people to attend would be the following.
First of all, I would be very sensitive to the Native American Indian history, culture, and traditions. I would show my respect for their culture and I would offer a respectful invitation to enroll in school, offering a series of classes that are required by the educational authorities but also including subjects related to the life, history, culture, and traditions of Native American Indian tribes of the region.
The living conditions I would provide would be according to the customs of these Native American people so they can feel comfortable in attending classes, not trying to impose any "modernity" that could make them feel awkward.
This way, Native American people would feel at home, showing an open attitude to learn about their history and traditions, but also about other American society and the world.