mod_rewrite for multiple applications

[eluser]obay[/eluser]
[quote author="Aken" date="1328608375"]Also obay, make sure you create something to handle calls to your root folder, which would normally default to index.php (like mywebsite.com would default to mywebsite.com/index.php) - so make sure you do something to keep your main .com from having a 404 error.[/quote]

@Aken, how would I do that, given my current .htaccess?