How can I tell drush to use another php.ini file? I've gone through the setup instructions on https://github.com/drush-ops/drush, but I can't seem to get drush to use a different configuration file, very frustrating.

I've already added the PHP_INI environment variable to my .bashrc and sourced it, seems like there is something I'm missing.
I copied my php.ini file to my home directory, and then ran:

$ PHP_INI=~/php.ini drush status


The "PHP configuration" line accurately reflected the new location of my php.ini file, so I believe this is still working on Drush 6.x and master.