Hi Isaac,
I just looked into this and found that the logic for the setting already exists, I just had not added it to the feature definition and created an entry in the resx file for it.
You can make it work now by adding this in the feature definition file under /Setup/applications/comments/FeatureDefinitions
<featureSetting
resourceFile="CommentResources"
grouNameKey=""
resourceKey="DateTimeFormat"
defaultValue=""
controlType="TextBox"
controlSrc=""
helpKey="BlogDateTimeFormat-help"
sortOrder="7000"
regexValidationExpression=""
/>
Then visit the setup page. The only thing you won't have until the next release is a good label format on the settings page.
Thanks,
Joe