load new dataset at runtime

Hi

In my application I'm downloading a new dataset based on what the user does. After that I need to load and activate that dataset. I'm using the VideoPlayback example for that. My problem is I don't know where to do this. I read the swappable datasets but since it was done with unity I couldn't understand much. If I do it in

doLoadTrackersData

it won't be called after initialization anymore and if I put it in a costum method like this:

public boolean costumLoadTrackersData()
	{
		// Get the image tracker:
		TrackerManager trackerManager = TrackerManager.getInstance();
		ImageTracker imageTracker = (ImageTracker) trackerManager
				.getTracker(ImageTracker.getClassType());
		if (imageTracker == null)
		{
			Log.d(
					LOGTAG,
					"Failed to load tracking data set because the ImageTracker has not been initialized.");
			return false;
		}

		if(mLoadNewTrackersData)
		{
			// Create the data sets:
			dataSetStonesAndChips = imageTracker.createDataSet();
			if (dataSetStonesAndChips == null)
			{
				Log.d(LOGTAG, "Failed to create a new tracking data.");
				return false;
			}
	
			// Load the data sets:
			if (!dataSetStonesAndChips.load(mTrackersDataPath,
					STORAGE_TYPE.STORAGE_ABSOLUTE))
			{
				Log.d(LOGTAG, "Failed to load data set.");
				return false;
			}
	
			// Activate the data set:
			if (!imageTracker.activateDataSet(dataSetStonesAndChips))
			{
				Log.d(LOGTAG, "Failed to activate data set.");
				return false;
			}
	
			Log.d(LOGTAG, "Successfully loaded and activated data set.");
			
			mLoadNewTrackersData = false;
		}
		return true;
	}

which is a copy & past of  'doLoadTrackersData'  and call it in a method in VideoPlayback.java, ImageTracker will be null. Can someone tell me how I should do this?