How to change the value of attribute in appSettings section with Web.config transformation

Is it possible to transform the following Web.config appSettings file:

<appSettings>
    <add key="developmentModeUserId" value="00297022" />
    <add key="developmentMode" value="true" />
    /* other settings here that should stay */
</appSettings>

into something like this:

<appSettings>
    <add key="developmentMode" value="false" />
    /* other settings here that should stay */
</appSettings>

So, I need to remove the key developmentModeUserId, and I need to replace the value for the key developmentMode.