As of version 7.0, IIS now ships with a standard rewrite engine. You may use the following configuration to create the appropriate rewrite rules.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="Imported Rule 1" stopProcessing="true">
                    <match url="^.*$" />
                    <conditions logicalGrouping="MatchAny">
                        <add input="{REQUEST_FILENAME}"
                             matchType="IsFile" pattern=""
                             ignoreCase="false" />
                        <add input="{REQUEST_FILENAME}"
                             matchType="IsDirectory"
                             pattern=""
                             ignoreCase="false" />
                    </conditions>
                    <action type="None" />
                </rule>
                <rule name="Imported Rule 2" stopProcessing="true">
                    <match url="^.*$" />
                    <action type="Rewrite" url="index.php" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>