Several online Bible websites, including BibleGateway.com and BibleStudyTools.com, have study notes, commentaries and overviews of the book of James using the King James Version. KJVHeartHelps.com also has free downloadable Bible study courses, one of which is on the book of James.
BibleGateway.com allows the user to select her preferred Bible version, including KJV, and to open the book of James for reading in that version. The Study This link then opens a menu of study helps for that passage, including a variety of notes and commentaries. Other ministry-based websites such as Pastor Charles Swindoll's Insight.org and Pastor David Platt's Radical.net have sermon series on the book of James, though they may not be specific to KJV.