Doubleclick DFP integration

I have just installed Admin Ads and was thinking if there is a way to use Google DFP to serve the ad. For DFP ads to serve there needs to be some JS in the template header and then the ad code added to a widget, which could be something like the Admin Ad plugin.

Can anyone tell me where exactly I would need to put the header JS to serve on all dashboard pages and can JS be pasted in the Admin Ads plugin?

Does anyone know of a plugin that can be used to add JS to the header globally?