I want to use the kernel-driver of parapin which i load during boot.
No, you want to use the user space module
Only the system is allowed to access the kernel space module.
Read the parapin documentation.

The problem with QParaport is that it is written for Qt3.
And I haven't had a look at this code for a very long time, so I don't know how easy it should be to port it to Qt4. (I forgot about this during the last post)
But I think it should be just a matter of changing the header deceleration.

As far as i understand you code sample - it needs root privileges.
The *code* doesn't require root privileges.
Under linux, you can set access privileges using the chmod command.
read the chmod command man pages for usage. (its simple)

i think i should use Qiodevice.h and not mixing old and new stuff together,
QIOdevice could be good if you'd want to implement the driver your self.
But if you use the ready made parapin driver, all you can do is either wrap it (as I did with QParaport) or use it directly.
It has nothing to do with mixing new and old.