The Big Boys normally just purchase the exclusive rights to the content and or they just re-brand the content; such being the pictures and or movies provided to them by such companies and or individuals making such content...
If you are an associate of the content producing company like
http://www.hustlercash.com ,
http://vivid.com also I should not leave out
http://adult.com , since they run this site ^^ , they will have promotional content for webmasters to promote their programs and will most likely allow you to create custom theaters...
The companies who do not make the content, but who resell such products and or services may not be as professional as the content producers and you might run across fly-by-night adult "services" who might have legal issues... It would be best to stay with those companies who are known to be the leaders for legal reasons...
Providing you have the time and energy... and providing you know how to write in HTML you should be able to design theater(s) that you like...
There are many admin types from different companies here to ask your questions...
Best of luck,