I think no such dynamic way like php-cgi you showed in first post.
while in .htaccess, you can put
php_value open_basedir /home/mydomain/public_html:/tmp
in lsws + lsphp, but not available in php-cgi way.
also in lsws php suExec mode, each account can have its own unique php.ini, to set everything include open_basedir.
I think they are just different approaches.