Thing is...google and other SE needs a content to rank your site. Google spider is not a human being who is going to come and watch your porn and then rate it. It needs words, alt descriptions, rich snippets. It is possible to manipulate it because all it does is calculating word density, back links, what neighborhood those links are coming from and how frequently your site is updated. Maybe add an erotic story to the site? Aggregate some content, spin it and post it, give those spiders some 'food for thought'.
Oh, and get you a good link building software and a windows server to run it 24/7.