Here is a code template which you may copy to your application namespace and adapt it to implement aspects in your qooxdoo application. For a far more advanced sample look at qx.dev.Profile.

/**
 * AspectTemplate.js -- template class to use qooxdoo aspects
 *
 * This is a minimal class template to show how to deploy aspects in qooxdoo
 * applications. For more information on the aspect infrastructure see the API
 * documentation for qx.core.Aspect.
 *
 * You should copy this template to your application namespace and adapt it to
 * your needs. See the comments in the code for further hints.
 *
 * To enable the use of your aspect class, some extra settings need to be done
 * in your configuration file.
 *  * Add a require of your aspects class to qx.Class
 *  * Set the variant qx.aspects to on
 *  * Set the setting qx.enableAspect to true
 *
 */
 
/* ************************************************************************
 
#require(qx.core.Aspect)
#ignore(auto-require)
 
************************************************************************ */
 
/** Adapt the name of the class */
qx.Bootstrap.define("your.namespace.YourAspectClass", {
 
  /** The class definition may only contain a 'statics' and a 'defer' member */
  statics :
  {
 
    __counter : 0,  // Static vars are possible
 
    /**
     * This function will be called before each function call.
     *
     * @param fullname {String} Full name of the function including the class name.
     * @param fcn {Function} Wrapped function.
     * @param type {String} The type of the wrapped function (static, member, ...)
     * @param args {Arguments} The arguments passed to the wrapped function.
     */
    atEnter: function(fullName, fcn, type, args) 
    {
      console.log("Entering "+fullName);  // Adapt this to your needs
    },
 
 
    /**
     * This function will be called after each function call.
     *
     * @param fullname {String} Full name of the function including the class name.
     * @param fcn {Function} Wrapped function.
     * @param type {String} The type of the wrapped function (static, member, ...)
     * @param args {Arguments} The arguments passed to the wrapped function.
     * @param returnValue {var} return value of the wrapped function.
     */
    atExit: function(fullName, fcn, type, args, returnValue) 
    {
      console.log("Leaving "+fullName);  // Adapt this to your needs
    }
 
  },
 
 
  defer : function(statics)
  {
    /**
     * Registering your static functions with the aspect registry. For more
     * information see the API documentation for qx.core.Aspect.
     *
     * @param fcn {Function} Function from this class to be called.
     * @param position {String} Where to inject the aspect ("before" or "after").
     * @param type {String} Which types to wrap (“member”, “static”, “constructor”, 
     *                       “destructor”, “property” or ”*”).
     * @param name {RegExp} Name(pattern) of the functions to wrap.
     */
    qx.core.Aspect.addAdvice(statics.atEnter, "before", "*", "your.namespace.*");
    qx.core.Aspect.addAdvice(statics.atExit, "after",  "*", "your.namespace.*");
  }
 
});

A job in your configuration could look something like this:

      "source" : 
      {
        "require" :
        {
          "qx.Class" : ["aspects.Aop"]
        },
 
        "variants" :
        {
          "qx.aspects" : [ "on" ]
        },
 
        "settings" :
        {
          "qx.enableAspect" : true
        }
      }

If you need some more information on configuring the generator, take a look at the Reference Listing of Config Keys.