Add Attribute to attributeset default and group general

mysql4-install-0.1.0.php

<?php

$setup = new Mage_Eav_Model_Entity_Setup('core_setup');

// Add attributes to the various sets
$attributeId = $setup->getAttribute('catalog_product', 'teaser');
$attributeSetId = $setup->getAttributeSetId('catalog_product', 'Default');

//Get attribute group info
$attributeGroupId = $setup->getAttributeGroup('catalog_product', $attributeSetId, 'General');

//add attribute to a set
$setup->addAttributeToSet('catalog_product', $attributeSetId, $attributeGroupId, $attributeId);