Shun, the committee decides who will perform their songs, and it's a well kept secret! The link that shows the former inductees says that along the top, no one knows until the show is in progress. Since it's not aired until weeks later, CBS will have time to hype whomever.

From that same link, I thought this was worth quoting here as they try to explain what this Honor means. The emphasis is mine.

The Honors have been compared to a knighthood in Britain, or the French Legion of Honor--the quintessential reward for a lifetime's endeavor. At the same time, the annual addition of new names to the roster of Honors recipients charts the international standard of excellence set by America's artists, as well as the aesthetic inspiration provided by artists of other nations who have achieved prominence on these shores.