Thanks @J-Hilk
The link provided needs other configuration.

My machine configuration is

Red Hat Linux - 32 bit
Qt creator 1.2.92, based on Qt 4.6.0 (32 bit)
Make version: GNU Make 3.81
Qmake version: 1.07a (Qt 3.3.6)

Please let me know what are the pre-requisites for a plugin. I want to create a menu item for Qt creator.

Thanks in advance.

Thank you, turned out it could be done like this:
QMAKE_POST_LINK += $SCRIPT_PATH $ARG1 $ARG2
No need for system()

ok that was the problem. In the Projects was the wrong build path. Now it works
thanks a lot