Do you means OLS 1.4.x, right? There is no mod_php in OLS for that version, but you can certainly run PHP as web server user:greoup instead of Changing to user:group.
no extra setting required within virtual host, simply just inheritage server php external app and script handler from server, where it should be either www-data:www-data, or nobody:nobody depend on your system.
However, if you want to change PHP to SuEXEC mode as user:group, you will need to create external app withit that virtual host and set user:group there. and set handler to the newly created VH level exteranl app.