Add block on the fly

config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Myspace_Fpcblock>
            <version>0.0.1</version>
        </Myspace_Fpcblock>
    </modules>
    <global>
        <blocks>
            <myspace_fpcblock>
                <class>Myspace_Mymodule_Block</class>
            </myspace_fpcblock>
        </blocks>
        <models>
            <myspace_fpcblock>
                <class>Myspace_Mymodule_Model</class>
            </myspace_fpcblock>
        </models>
        <events>
            <controller_action_layout_render_before_cms_index_index>
                <observers>
                    <add_time_before_content>
                        <class>Myspace_Fpcblock_Model_Observer</class>
                        <method>prependTimeBlock</method>
                    </add_time_before_content>
                </observers>
            </controller_action_layout_render_before_cms_index_index>
        </events>
    </global>
</config>

Observer.php

<?php

class Myspace_Fpcblock_Model_Observer
{

    public function prependTimeBlock($observer)
    {
        /** @var $layout Mage_Core_Model_Layout */
        $layout = Mage::app()->getLayout();
        $block = $layout->createBlock(
            'Mage_Core_Block_Text',
            'myspace_fpcblock_time',
            array('text' => "Generation Time: " . date('H:i:s'))
        );
        $layout->getBlock('content')->insert($block);
    }
}