According to FDA:
1) Go to www.regulations.gov
Search for docket FDA-2009-N-0441-0001 (or type "Internet promotion"
in the search box)
The search results will display the FR notice and under the "Actions"
column on the far right there are 2 options ("Submit a Comment" &
"Open Docket Folder")
Click on "Submit a Comment" and enter the requested information
(specify that you are just registering to attend in the comment box on the right)
Submit your information
You should then receive a tracking number that confirms your registration