It actually worked with the following:
curl -sS https://getcomposer.org/installer | php-5.4 -d 'extension=phar.so'
Composer successfully installed to: /home/cosmicd/composer.phar
Because I had no way to really know where my site's directory is, it seemed to be installed in the right user dir at least when I removed the whole installdir bit"
Still some problems: by doing the original line (now I also modify it to use php-5.4 , it still gives the error that phar isn't installed
curl -sS https://getcomposer.org/installer | php-5.4
Also, still, according to fork's guide, I need to be able to use "composer" as a command and that doesn't work as well.