def installParcel(parcel, old_version=None):

....

    # The periodic task that uploads logfiles in the background  
    PeriodicTask.update(
        parcel, 'eventLoggerUploadTask',
        invoke = 'eventLogger.UploadTask',
        run_at_startup = True,
        active = True,
        interval = timedelta(minutes=2))


then...


class UploadTask(object):
    def run(self):
        print "HELLO WORLD"
        return True