Thanks for the reply. These instructions I had already been found.
After entering in putty: /usr/local/psa/admin/sbin/autoinstaller --select-release-current --install-component php53
The following message appears: Warning: following component(s) not found: 'php53'
You already have the latest version of product(s) and all selected components
installed. Installation will not continue.
I can not find even in Plesk: PHP5.3 support
The other points I do not understand.