[TYPO3-dev] language label in language other than system language

[WK]

Dear list,

as newbie to the list, i beg to apologize if i'm missing the topic:
I need to get a language entry in a language other than the current 
system language from a locallang.xlm. Tweaking  tslib_pbase::LLkey 
didn't do the trick
e.g. current language is English and i do a
  $this->LLkey = 'de';
  $word = $this->pi_getLL('label');
Neither worked changing the sys_language_id and reloading the language 
tables
  $GLOBALS['TSFE']->sys_language_uid=1;
  $this->LOCAL_LANG_LOADED = 0;
  $this->pi_loadLL();
What am I missing?
And talking of missing: I also missed a sql_err_no() in the database 
abstraction library t3lib_db...

Thanks