How to upgrade magento 1.5 mage all latest to the beta version

is it possible to do this through mage? if so how . when I try

    ./mage install http://connect20.magentocommerce.com/communi开发者_如何学Goty Mage_All_Latest

it just tries to install the same version 1.5.1.0 putting upgrade would do the same. how to tell mage install to install the beta version?

I found it. I need to set mage to use BETA:

  ./mage config-set preferred_state beta

found on this site: http://www.yireo.com/tutorials/magento/magento-administration/1294-magento-15-mage-command-line