[TYPO3-mvc] Translate a model in controller action?

[Gerhard Mehsel]

Hello,

I need a model and a translation of that model.
Therefore I create a model in a controller action, add it to the 
repository and do a persist. At this moment I know, that I need this 
model in a second language as well.

How can I add a translated version of that model, also? AFAIK I cannot 
simply create a second instance and set the parent/sys_language_id.

Thanks for hints and best regards,
Gerd