Here are the details of their FAQ on this topic:
C17: What “Web Browser” is supported by TTB to use COLAs Online?
To take full advantage of COLAs Online, it is recommended that you use only the Microsoft Internet Explorer (IE) 5.0 or higher when accessing COLAs Online. Netscape or Firefox are not supported and do not work consistently with COLAs Online. In addition, even though the Apple/Macintosh platform is not currently supported by TTB, if you do chose to use a Mac computer you must utilize the web browser Safari 1.2 or Internet Explorer (IE) 5.2 or higher. In addition, there are also known technical problems with the AOL interface accessing COLAs Online when using the IE browser within AOL. Because of this TTB does not recommend the use of the IE web browser within AOL when accessing COLAs Online.Here also is a link to their other various helpful topics on wine labeling: http://www.ttb.gov/wine/wine-labeling.shtml