If everything is relative to the pages
folder, then you can use some simple searching and replacing. This isn't the best programming practice, as it is not as flexible (going from relative to absolute in this type of context is relying on a number of factors working properly) as it should be, but it will work.
$.get('html/pages/page1.html', {}, function(data, status, xhr) {
var updatedData = data.replace(/\.\.\/(images|css|js)+/g, "http://www.mywebsite.com/html/$1");
$('#content').html(updatedData);
});
Edit:
You could also use a proxy script and rewrite/route all requests to this folder to the proxy script. I don't know what server-side technology you are using, but you could do this:
Using .htaccess
(or the like), redirect all requests directed to this folder to another script in your codebase. In the script, look for the path that is incoming to the script, load the original output contents, perform a search/replace and output the contents to the buffer. In addition, you can set up caching on the server so that the client would cache the requests lowering the processing overhead that you might experience (though, I would anticipate that to be fairly minimal).