[CentOS] using conf.d files to override options in httpd.conf

Like many of you, I like to avoid modifying 
/etc/httpd/conf/httpd.conf as much as possible. Instead, 
modifying or adding files in /etc/httpd/conf.d

However, because /var/www/html is declared within the main 
httpd.conf and certain directives are set along with 
"AllowOverride None" (thus forbidding use of .htaccess), it 
seems like the only way to override any of these options is 
to modify httpd.conf directly. If nothing else, at least 
setting "AllowOverride" to something besides None.

Is that correct? Or does anyone know of a way to leave 
httpd.conf pristine, yet still override or set directives 
for /var/www/html?

johnn