[TYPO3-mvc] How to extend the felogin extension?

[Stefan Kruse]

Hi,

i need to extend the felogin sys extension. I see that I would rework in
Typo3 6.0.

How can I use xclass to extend some functions from this extension.

I found:

GLOBALS -> SYS -> Objects: But how does it work exactly? 

Would be nice if someone could give me a hint how to extend the felogin
extension with a own Extbase extension.

Thanks a lot
Stefan