Sloan-Kettering does not provide funds for people being treated there, or to bring people to the US -- you have to have/raise the money yourself. There are legal requirments through the immigration dept -- the last I heard, the US govt required that you have at least $300,000 to pay for treatments at Sloan.
If you look on the Sloan website (www.mskcc.org) you should be able to get contact info for someone that can help explain the requirements -- as I said, many of them are imposed by the US government, not the hospital. I know it seems like a lot, but many people have come to Sloan from around the world -- most people are good at heart and will be as generous as they can be. It is amazing to see how communities open their hearts to help a child with cancer .