How to tweak the Looper/Handler logic to execute a fixed number of tasks at the same time?

Question

In an app of mine I've successfully implemented the "Pipeline Thread" concurrency pattern to execute certain tasks in sequence (in a queue):

@Override
public void run() {
  try {
    Looper.prepare();
    handler = new Handler();
    Looper.loop();
  } catch (Throwable t) {
    Log.e(TAG, "halted due to an error", t);
  }
}

then, to schedule an operation:

handler.post(new Runnable() {
  @Override
  public void run() {      
    // this will be done in the Pipeline Thread      
  }
});

with

handler = new Handler();

declared into the activity’s onCreate()

(ref: http://mindtherobot.com/blog/159/android-guts-intro-to-loopers-and-handlers/)

What I'm trying to figure out is if I can some way tweak this pattern to execute a (fixed) maximum number of those tasks at the same time, as it happens with AsyncTask and the THREAD_POOL_EXECUTOR, as seen here: https://stackoverflow.com/a/9509184/1865860

The problem is that I don't have any idea (and knowledge) about where to start to take a cue on this.

Any help is much appreciated. Thanks.