Most settings that you would place in your php.ini can also be placed in a .htaccess or in the apache configuration for that site. For example one of my virtual hosts has this in the .htaccess

    php_value display_errors 1
    php_value register_globals 0
    php_value short_open_tag 0
    php_value magic_quotes_runtime 0
    php_value magic_quotes_gpc 0
    php_value session.name "PHPSESSID_SITEBLAH"
    php_value session.gc_maxlifetime 57600
    php_value session.gc_probability 1
    php_value session.gc_divisor 500