Using EC2 as a Cloudfront Origin Server

You have to use the API to create a DistributionConfig that uses CustomOrigin (rather than S3Origin). Some documentation on how to do so here: http://docs.amazonwebservices.com/AmazonCloudFront/latest/APIReference/index.html?DistributionConfigDatatype.html#CustomOriginChildElements

Then you have to create a Distribution using that DistributionConfig: http://docs.amazonwebservices.com/AmazonCloudFront/latest/APIReference/index.html?CreateDistribution.html

More information on Distributions can be found here: http://docs.amazonwebservices.com/AmazonCloudFront/latest/DeveloperGuide/index.html?WorkingWithDistributions.html

I believe once you've created the Distribution, you can manage it from within the AWS Console, but you can't yet create them there.

Now-a-days you can setup Custom Origin via the AWS Web console.