Dynamic CSS/Javascript in Twig using Silex/SilexExtensions and Assetic

What I want to do: Get CSS properties from a database and dump it into a less file. Then apply a less/yui compress-filter on it and dump the output in my twig template.

Let me just come to the point right away:

I have a PHP web application using Silex and Twig as template engine. In order to process and minify the css/js files I'm trying to use Assetic and the Silex-Twig/Assetic-Extensions.

I have registered the silex extensions and set the filters I want to use. Now I have no clue whatsoever on how to dump the files inside my twig template. Google Search keeps me in the dark. Since the properties in the lessfile can change per request I think there is no way of a static delivery of the files.

This is my implementation of the silex extensions:

$oApp = new Silex\Application();

//$oApp['autoloader']->registerNamespace('Assetic', DIR_VENDOR.'/assetic/src');
//$oApp['autoloader']->registerNamespace('SilexExtension', DIR_VENDOR.'/silex-extension/src');
//$oApp['autoloader']->registerNamespace('Twig', DIR_VENDOR.'/twig/lib');

$oApp->register(
    new Silex\Provider\TwigServiceProvider(), array(
        'twig.path' => DIR_ROOT.'/src/templates',
        'twig.class_path' => DIR_VENDOR.'/twig/lib',
    ),
    new SilexExtension\AsseticExtension(), array(
        'assetic.class_path' => DIR_VENDOR.'/assetic/src',
        'assetic.path_to_web' => DIR_ASSETS,
        'assetic.options' => array(
            'debug' => false,
            'formulae_cache_dir' => DIR_TMP.'/Assetic/cache',
            'twig_support' => true
        ),
        'assetic.filters' => $oApp->protect(function($fm) {
            $fm->set('yui_css', new Assetic\Filter\Yui\CssCompressorFilter(
                DIR_YUI.'/yuicompressor-2.4.7.jar'
            ));
            $fm->set('yui_js', new Assetic\Filter\Yui\JsCompressorFilter(
                DIR_YUI.'/yuicompressor-2.4.7.jar'
            ))