Mango Languages requires the following configuration in config.txt/ezproxy.cfg:
Title Mango Languages
URL http://libraries.mangolanguages.com/<institution_name>/start
DJ mangolanguages.com
DJ libraries.mangolanguages.com
HJ http://libraries.mangolanguages.com/<institution_name>/start
Replace <institution_name> with your institution name that is available from Mango Languagues.