WordPress Plugin
This plugin will modify the links in your posts to be Ewerls. You will need to input your API Key in the "Ewerl" plugin administration screen after installing and activating the plugin.
This plugin has been tested on WordPress 2.5
This plugin will only modify posts created after the activation. Previous posts would need to be edited and resaved to have their links converted in to Ewerls
Your webhost will need to allow remote file opening for this plugin to work.