You could make a page that sits in the root directory of the site (i.e. at www.mysite.com) which redirects to /forum. Upload the icon file to the phpbb root directory and edit your overall_header template file. See here
ok i did what u said:
i upload the favicon.icon to puplic_html/forum
then i edit the overall_header at forum/template/mystyle/
but nothing happen! i can't see my favicon. any suggestions?
Please note the extension is .ico not .icon
So should be favicon.ico
The truth is out there.
Unfortunately they will not let you anywhere near it!