Log in to your Managed Hosting Server via SSH
Add a hidden binary folder in root and add a symlink to a more up-to-date php version
cd ~/
mkdir .bin && cd .bin
ln -s /usr/local/bin/php5.6.2-cli php
cd ~/
source .zshrc
Add the new binary folder to the PATH Variable
echo "export PATH="\'"$HOME/.bin:\$PATH"\' >> .zshrc
Reload .zshrc with
source .zshrc
Install Composer with
curl -sS https://getcomposer.org/installer | php
Done.
Check the installation with
$ composer -V
You should see something like this
Composer version 99f5b5a2383604d73c23aac19cea91a6b047171f 2014-01-12 20:13:00
Your version will probably differ.