You can "Allow from xxx.xxx.xxx.xxx" (where xxx.xxx.xxx.xxx = some IP) to the below code in .htaccess thereby permitting access for the owner and others as needed.
<Files ~ "\.(inc|class)$"> Deny from all </Files>
becomes:
<Files ~ "\.(inc|class)$"> Deny from all Allow from xxx.xxx.xxx.xxx </Files>
You can add multiple IPs separated by "," e.g.
Allow from xxx.xxx.xxx.xxx, xxx.xxx.xxx.xxx