How can I set a DevelopmentTeam in TargetAttributes?

I've been hunting around but can't figure out how to set an arbitrary attribute on the project.

Specifically, a fresh XCode project with no "Team" setting is missing an entry for the target in its TargetAttributes object. I need to create an object and add it into the attribute.

The 'attributes' property is simply a hash, so how would I do this? Any help is much appreciated, thanks.