I'd like to deny access to all scripts from inside a particular directory except the one that I specify 

I'm thinking something like this

<Directory /home/site/site1/webdir/>
	<FilesMatch "^index\.php$" >
		#In here I'd like to say that for the file that matches the regular expression 
		# set an allow from all
		# but for anything else that doesn't match, it should be a deny from all
	</FilesMatch>
</Directory>