Just use an .user.ini file in your SugarCRM root directory. You can place the configuration options there, even when using a shared host.
In order to get rid of all warnings and notices from php I created a .user.ini file in the SugarCRM root directory with the following content:
error_reporting = E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED & ~E_WARNING