This is how to allow users to set config values in their .htaccess files.

This would mainly be used for things like mod_rewrite directives.

# /etc/httpd/conf/vhosts/siteN.include
# user customizations can be added here.
<Directory /home/.sites/xxx/siteN/web>
AllowOverride All
</Directory>

"Directory" should be the DocumentRoot value from:
/etc/httpd/conf/vhosts/siteN

The code should be added to:
/etc/httpd/conf/vhosts/siteN.include

Restart apache:

/etc/rc.d/init.d/httpd restart