WordPress.org

1. Unzip and upload the "bbSigPress" directory into "wp-content/plugins/"
2. Activate it on your plugin management page.
3. Setup your accounts under the new "bbSigPress" option of the settings menu
4. That's it, you're done!

Update

• Override the "bbSigPress" directory in "wp-content/plugins/"

Update from within Wordpress Admin Panel of course also works.