TWAIN Bridge is not yet publicly available as TWAIN Direct is not yet officially available for release. Please check back on the website from time to time for developments. There will be new information coming soon. The TWAIN Working Group sincerely appreciates your patience!
I would suggest contacting a representative at Canon directly to gain access to the proper download. TWAIN supplies the tools and standard for manufacturers to develop TWAIN drivers. It is up to the manufacturer to develop the TWAIN driver for their machines and distribute to users.