Here is how to use CAT to get the fields for all selected entries:

using Laserfiche.RepositoryAccess;
using Laserfiche.ClientAutomation;

.....

using (ClientManager clientmgr = new ClientManager())
{
    foreach (ClientWindow window in clientmgr.GetAllClientWindows(ClientWindowType.Main))
    {
        MainWindow mainWindow = (MainWindow)window;
        try
        {
            List<int> selectedEntries = (List<int>)mainWindow.GetSelectedEntries();
            foreach (int entryId in selectedEntries)
            {
                RepositoryConnection conn = mainWindow.GetCurrentRepository();
                string serializedConnection = conn.GetConnectionString();
                using (Session session = Session.CreateFromSerializedLFConnectionString(serializedConnection))
                {
                    EntryInfo entryInfo = Entry.GetEntryInfo(entryId, session);
                    FieldValueCollection fvc = entryInfo.GetFieldValues();
                    foreach (string fieldName in fvc.FieldNames)
                    {
                        object objFieldValue = fvc[fieldName];
                        string fieldValue = "";
                        if (objFieldValue is object[])
                        {
                            // Multivalue field
                            foreach (object subValue in (object[])objFieldValue)
                            {
                                if (!String.IsNullOrEmpty(fieldValue))
                                    fieldValue += ", ";
                                fieldValue += subValue.ToString();
                            }
                        }
                        else if (objFieldValue != null)
                            fieldValue = objFieldValue.ToString();

                        Console.WriteLine(String.Format("{0}: {1}", fieldName, fieldValue));
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}