if ($this->modelClass == 'DataObjectName')
{
   $query->where[] = "ShowInCMS = true";
}

class MyCustomAdmin_CollectionController extends ModelAdmin_CollectionController {
   
   // copied from ModelAdmin
   function getResultsTable($searchCriteria) {
      
      $summaryFields = $this->getResultColumns($searchCriteria);

      $className = $this->parentController->resultsTableClassName();
      $tf = new $className(
         $this->modelClass,
         $this->modelClass,
         $summaryFields
      );

      $tf->setCustomQuery($this->getSearchQuery($searchCriteria));
      $tf->setPageSize($this->parentController->stat('page_length'));
      $tf->setShowPagination(true);
      // @todo Remove records that can't be viewed by the current user
      $tf->setPermissions(array_merge(array('view','export'), TableListField::permissions_for_object($this->modelClass)));

      // csv export settings (select all columns regardless of user checkbox settings in 'ResultsAssembly')
      $exportFields = $this->getResultColumns($searchCriteria, false);
      $tf->setFieldListCsv($exportFields);

      $url = '<a href=\"' . $this->Link() . '/$ID/edit\">$value</a>';
      $tf->setFieldFormatting(array_combine(array_keys($summaryFields), array_fill(0,count($summaryFields), $url)));
      
      // performCanViewOnEachItem
      if($tf->sourceItems()){
         $tf->setCustomSourceItems($this->performCanViewOnEachItem($tf->sourceItems()));   
      }
      
      return $tf;
   }
   
   function performCanViewOnEachItem($sourceItems){
      if($items = $sourceItems){
         foreach($items as $item){
            if(!$item->canView()){
               $items->remove($item);
            }         
         }
         return $items;   
      }
   }
}

//only current user items, except for admins
   function canView(){
      if(!Permission::check('ADMIN')){
         if($this->AuthorID == Member::currentUserID()){
            return true;   
         }
      } else {//if admin
         return true;
      }
   }

   //same as canView
   function canEdit(){
      return $this->canView();
   }
   //only when there are less then 10 SomeChildClasses
   function canCreate(){
      if($this->SomeChildClasses()->Count() <= 10){
         return true;
      }
   }
   //only if not more than a week old.
   function canDelete(){
      if(!Permission::check('ADMIN')){
         if(strtotime($this->Created) >= strtotime(date('Y-m-d', strtotime('-1 week')))){
            return true;   
         }
      } else {//if admin
       return true;
}      
   }