Trying using this video as a reference https://software.intel.com/en-us/videos/integrating-a-new-service. It might work for you.
https://software.intel.com/en-us/videos/oauth-2-and-services. It uses Foursquare as an example.
Here's the link to the whole app designer video tutorials list: https://software.intel.com/en-us/xdk/videos/intel-xdk-app-designer
The Services tab was moved into the Develop tab. It's in the lower left corner. When you work with that corner, it'll open up larger