Local php.ini ignored

[IanR]

Trying to figure out what I need to do to make localized php.ini files work.

They work on my webhost but not in xampp/windows/php5.3.1.

I find that putting php directives in .htaccess works in xampp, but not on my webhost.
So I have a catch-22 here. I need to set a few directives in a way which will work in both cases.

I'm guessing that the "Scan this dir for additional .ini files" (none) property in phpinfo() might be something to do with this. Unfortunately it gives no clue as to where this property is set or what syntax is used.