Gatekeeper

I recently found that a QB app was denied runtime privileges as it didn't pass Mountain Lion's Gatekeeper security check for having been created by an approved developer.

Would that application have passed muster with Gatekeeper if it had included in its Identifier meta information the name of an approved developer?

My understanding was that such code signing needed to be done during the process of developing an application within Xcode and could not be done any other way at all.

https://developer.apple.com/library/mac/#documentation/Security/Conceptu...

Is there any way that an application other than Xcode that produces small applications, like Quartz Builder, could have an option for registered Apple developers to incorporate the appropriate certification Gatekeeper requires of Apple application developers?