[TYPO3-mvc] own validator in TYPO3 6.x namespaces

[Domi]

Hello,

during the upgrade of my extension to namespaces for TYPO3 6 my own 
validator is not working anymore. Tried several things but I am very 
confused, it seems that namespaces are not supported for validation.

How can I call own validators in

A) Controller
B) Model

Or do I simply not renaming the Validators and keep the "Tx_..." syntax?

Thanks for helping,

Dominic