Uploading Directly to S3 on CORS without Flash, from HTTPS hosted site

We are looking at an option for uploading large files (in ~100MB+) to S3.

The html-form also contains other meta information about the file, that will be stored in our application database and not in S3. Based on the success/failure of the file-upload to S3, the metadata about the image will be inserted to our application DB.

The application is on Ruby-on-Rails stack and is HTTPS enabled. Form submission to S3, is ruled out, so is a flash based upload. All the other choices we have considered, have their own limitations.

1. Direct JS upload is not possible because of cross-domain (CORS) limitation with S3.

2. Configuring the HTTP server (nginx) with OPTIONS as mentioned here (http://zefer.posterous.com/pure-html-ajax-solutions-to-upload-files-to-s). But the application (i.e, nginx) will run behind ElasticLoadBalancer on HTTPS. Is there a better way to handle this requirement on ELB ?

Are there other good patterns for this requirement in AWS World ?

Thanks,Sriram