Control Panel / Custom Islands
Pick an island (let's say #1) and click "Edit".
Name: Rename to Site Links or whatever you want.
Body: Put your site link HTML between $body = <<<EOF and EOF;
Click "Update Custom Portal Box".
Once you've done that you need to go to Control Panel / Portal Layout and you will see your new "Site Links" Custom Island in the list. All you need to do is select where you want it to appear with the Left Column / Right Column selectors.
Done!
