[TYPO3] BE List view editing with PHP?

[Jeroen Visser | ROQUIN E-Solutions]

Hi,
I have made extension B which requires extensions A. The id's are mm 
relations.
In the backend, module list view => sysfolder with ext data, I want to 
show the username instead of the id that is shown right now. I have 
tried to accomplish this by calling a userfunc from ext_tables.php no 
luck there.

If someone know's please let me know. Thanks in advance.

Kind regards,
Jeroen