[TYPO3-english] locallang_db.xml and FE

[mario]

Hello

I have developed a very simple fe-plugin extension. 

I am trying to output into the FE values from locallang_db.xml. 
After some very simple minded attempt, I understand that something as 
$out .= $this->pi_getLL('locallang_db.xml:tx_myext.myfield...', 'def');
is NOT going to work. 

I am not able to see if and how I could use methods from the class
language (lang.php)

Maybe somebody has worked out this already.
Any hint or advise is very welcome. 
Thanks

happy typo3
mario