Implementation of V-USB

So, I have finally decided, that i want to make a project with my Arduino Nano, that was laying on the shelf. The project should be a keyboard for my laptop. But after reading few posts, I see, that I should use the V-USB library, because nano does not support HID protocol. I have found a manual, but I do not understand it. Any help where is your project's firmware source code directory? Or how to make sure that makefile contains rules to convert *.S and *.c? And the last, where is firmware's Makefile directory?

Manual: Simply copy the entire usbdrv subdirectory into your project's firmware source code directory. Then edit the firmware's Makefile and add the following object files to your binary:

usbdrv/usbdrv.o
usbdrv/usbdrvasm.o
usbdrv/oddebug.o
Then make sure that your Makefile contains rules to convert *.S and *.c to object files.

I´ve tried, but I cannot import it into my Arduino IDE.

I cannot import it into my Arduino IDE

What did you try ?

Why make your life difficult? Use a processor with native USB and HID support.

branislavmateas:
So, does anyone know, how to make it work?

You stopped quoting the intallation instructions one sentence before:

See the Makefiles in the examples subdirectory for an inspiration.