The toolbar items which are available in the administration interface are not suitable for eZ Flow. I order to add login or search box, you have to create a new block types in the block.ini.append.php (see extension/ezflow/settings/block.ini.append.php for the reference) then put your xhtml code in the block templates. See online documentation how to create a new blocks. Those blocks you can later add in the edit mode for your frontpage to specific zone.