There’s no built-in way other than the all-or-nothing preload checkbox to control resource preloading at the moment, but I do consider this a great feature request needed by many people.
However, you could write code yourself to do preloading. Basically you could do this as an on scene load event where you start downloading images needed by other scenes. Preloading is pretty easy; you can just make a dummy image and set the src to your URL (you’ll need to maintain your own list). Because of browser caching, once an image has been loaded it can be used by other elements without needing another load. The basic code looks like:
var completionHandler = (function (e) {
img = this;
// do something...
});
img.onload = completionHandler;
img.onerror = completionHandler;
img.onabort = completionHandler;
img.src = resourcePath; /* some variable containing the URL */
You’d optionally need some code to prevent going to a scene where the image has not been loaded yet.
Note that this is only the case for images. If you want to preload audio, you must do that through Hype’s current mechanisms. Hype doesn’t preload video at all.