Well, I have finally managed to do it. Upload to S3 from my browser through my website. After my quick success with pulling objects from AWS S3 (ref: AWS S3 - Connecting and Getting a List of Objects), I thought it would be just a hop skip and a jump to upload files to S3.
As it turns out, It is. In a not really kinda way. The problem isn't with uploading to S3, that is actually extremely well documented (Ref: Browser Uploads to S3 using HTML POST Forms as well as other AWS Documents). The issue was with signing the post request with ColdFusion. I was eventually able to work out my signing issue thanks to a Post from @BenNadal (ref:Uploading Files To Amazon S3 Using A Form Post And ColdFusion).
It turns out that I was missing the part about decoding the policy when encoding my signature. This was missing piece. Once I had that in place, it was a simple matter to complete the form. The result of which, is now I can upload direct to and serve images from Amazon S3!