CNN said Friday that guests will visit with King on set and by satellite. They will also participate in the program's telephone banks taking viewer calls.
Ryan Seacrest will host an online suite for viewers using social media like Facebook.
"Disaster in the Gulf: How You Can Help" is aimed at raising funds for the United Way, National Wildlife Federation and The Nature Conservancy. The telethon will air 8 p.m. to 10 p.m. Eastern.