I'm going through the Site.com Workbook, trying to add a datatable to a site.com site, but the only data available from a custom object are the standard fields.  I have edited the guest user profile via the site configuration link in the Overview tab of the site to enable read access to the custom object.  I can not find where to set field-level security on the custom object because the guest user profile is not included in the list of available profiles for the objects FLS.