How do I use AWS S3 with Full (Strict) Mode turned on

ssl
caching

#1

This article (https://support.cloudflare.com/hc/en-us/articles/200168926-How-do-I-use-Cloudflare-with-Amazon-s-S3-Service-) describes how to set up a CNAME for an S3 bucket and use SSL.

The section that I’m interested in is here:

Using SSL with AWS S3 and Cloudflare:

After creating the above CNAME with CloudFront or an ELB set up with a SSL certificate, you will be able to use Full SSL with Cloudflare, but not Full(Strict). If you want to use Full(Strict) SSL, you will need to set up AWS ELB with a custom certificate signed by a trusted Certificate Authority (CA).

I do not understand how I connect my ELB with a custom cert to Amazon S3. Do I need to use a web server to pass the images through the ELB? Is there a serverless method using the ELB?