If you do not wish to move your entire server to use alpha mode (or beta) but keep the mainline in stable, but still wish to install the actual package; you just
enter the information from channel and on and the plug in will install.
$:/var/www/magento$ ./pear install magento-community/Florent_Piwik
Failed to download magento-community/Florent_Piwik within preferred state "stable", latest release is version 0.4, stability "alpha", use "channel://connect.magentocommerce.com/community/Florent_Piwik-0.4" to install
$/var/www/magento$ ./pear install channel://connect.magentocommerce.com/community/Florent_Piwik-0.4
downloading Florent_Piwik-0.4.tgz ...
Starting to download Florent_Piwik-0.4.tgz (4,163 bytes)
.....done: 4,163 bytes
install ok: channel://connect.magentocommerce.com/community/Florent_Piwik-0.4
The Magento Connect uses values stored in the directory downloader to know where to connect, where to save files etc. The problem is that these paths are hard coded into files at the installation of Magento.
If you wish to move your installation to a new path then this will break the Magento Connect in the admin panel.
The version that I find easiest to do on the new server is to log in using ssh and then run “./pear mage-setup .” That will reset the aboslute paths that are stored in the downloader directory.
Another option would be to re install magneto:
Upload a fresh copy of Magento onto the new server (don’t run the installer yet)
Copy over your Themes/Templates, Skins, Images, and Custom Modules
Dump the database from the original, and import the database to the new site
Run the installer – and enter all the necessary info
Go into the Magento Connect Manager, and install this extension: magento-core/Mage_All_Latest