Adaptive Caching Directives

We are an independantly operating hosting company with our own proprietary browser-based website builder interface. As a shared hosting company, our users require fast, responsive and efficient websites that can cache resources (such as stylesheets or images) as necessary to provide the optimum experience for all visitors. However, as a live website builder, our users require an up-to-date, live vision of what their website looks like while they're editing it, without any cached resources (like stylesheets or images). You will need to be an information technology expert with an advanced understanding of Apache and .htaccess, with the knowledge and abilty necessary to create a set of caching directives that will allow seamless integration of both of our user scenarios. The adaptive caching directives must not be programatic (ie PHP) as that will only go as far as any web page content, not the physical resources. The adaptive caching directives must be in a file that can be copied into our existing customer sites, so that we can settle this issue for them retroactively.