Maybe create a category attribute like a boolean (e.g. addbacklink) that means : add back link in this category and do something like :

$category = Mage::registry('current_category');
if($category && $category->getData('addbacklink')){
//add link to current product view
}

Maybe create a category attribute like a boolean (e.g. addbacklink) that means : add back link in this category and do something in product view like :

$category = Mage::registry('current_category');
if($category && $category->getData('addbacklink')){
//add link to current product view
}

Best way should be create a custom block and add it via layout