[TYPO3-english] Changing translations in extensions using xml files

[Sören Kracker]

Hello,
I use felogin extension and want to change some strings there.
Sure I can do something like "LOCAL_LANG.de.ll_forgot_reset_message = my 
message"
but the site has 10 languages and I need translations in xml files so 
they can be translated by a translation office.
LOCAL_LANG doesn't support stdWrap and the strings are loaded from 
extension's locallang.xml or translated xml files in l10n. If I change 
those the changes will be overwritten on the next update.
I could also change the message using "forgotMessage_stdWrap.cObject" 
but that changes the text for both ll_forgot_reset_message and 
ll_forgot_reset_message_emailSent.
So how can you use your own xml files?