[TYPO3-mvc] Understanding Problem: using data of core tables and relations

[Sören Kracker]

Hi,
just started developing with extbase and fluid.
I have following setup (created with extension_builder):
Model_Catalog (fields: filename, category, catalogtype)
Model_Category (name, parent)
Model_CatalogType (name)
all 3 got a repository

has to be integrated:
Model_CatalogLanguageType (name)
this one got no repository (yet?)

Everything works fine in saving catalogs with a specific category and a 
catalog type (as Backend Module).
Now I have to add a language selection for the catalog too. There are 2 
different languages for one catalog and the selection (in new/edit form 
of catalog) should contain the values from sys_language table.
The submitted data has to be saved into CatalogLanguageType. The table 
consists of the catalogid, the language uid and the title of the catalog 
in the corresponding language.

So my question is: How do i realize that? I've tried some things but 
couldn't get a result. Should I create a repository and model for 
mapping the sys_language table? And if I do, how do I connect my 
CatalogLanguageType? Or is my setup totally wrong? Any hints are greatly 
appreciated, especially regarding realization in TCA and 
Controller/Repository.