Script Filter Options arg autocomplete icon icon_fileicon icon_filetype subtitle subtitle_alt subtitle_cmd subtitle_ctrl subtitle_fn subtitle_shift text_copy text_largetype title uid valid

valid must be either true or false, but all of the others must be strings.

You pass them as an array:

$workflow = new Alphred;
    'arg' => 'this is an argument to be passed on',
    'autocomplete' => 'when I press tab, this appears',
    'icon' => '/path/to/icon',
    'icon_fileicon' => 'info.plist',
    'icon_filetype' => 'php',
    'subtitle' => 'This is a subtitle',
    'subtitle_alt' => 'This is an alternate subtitle',
    'subtitle_cmd' => 'This is the command subtitle',
    'subtitle_ctrl' => 'This is the control subtitle',
    'subtitle_fn' => 'This is the function subtitle',
    'subtitle_shift' => 'This is the shift subtitle',
    'text_copy' => 'This is the text when you copy',
    'text_largetype' => 'This text will be shown for large type',
    'title' => 'This is the title',
    'uid' => 'This is the uid',
    'valid' => true,

Now, that might not work out so well because you have some conflicting information between icon, icon_fileicon, and icon_filetype. Also, the alternate subtitles (when you press the modifier keys) might not work unless the script filter is attached to an action that has those modifier keys.