mod_php -v- PHP as a CGI binary

My webhost does not run PHP as mod_php because they don’t want to allow access to database services to user ‘nobody’ – hence perl, PHP are not run as Apache mods, they are executed with the account’s shell user permissions; and their corresponding MySQL accesses cannot overflow into someone else’s database account.

As a consequence of this set up, I cannot install WordPress without figuring out which .php files are called via URL so that I can chmod 755 and add the #!shebang to each.

I got as far as modifying index.php and wp-admin/install.php but the latter returns HTTP 500 (server error).

Is there hope of me continuing to use WordPress with this particular webhost?