Oh it's  alright. Having read the manual ,I've managed to use the ndisgen utility to integrate the .sys&.inf into the kernel but ...
It failed at the last step, namely the "kernel module generation" and the following lines are present:
Generaing Makefile... done.
Building kernek module... /usr/share/misc/windrv_stub.c:57:20: windrv.h: No such file of directory.
mkdep: compile failed
So, what could be the solution to this? Shall I manually get those two  files (windrv_stub.c & windrv.h) and place them in the directory /usr/share/misc/ or should I install something else all over?
Thanks!