CC=/usr/bin is definitely invalid
CC should point to an executable, to the c compiler. /usr/bin is a directory

gcc is most probably the compiler that would be used to compile gcc.
and since you don't have the gcc compiler, you cannot compile gcc.
...
i don't know what this system of yours is, and why it's 10 years out of date, and why all of a sudden you need support for a 5 year old network adapter... but it seems that problems are just piling up here, because it's some sort of crippled (and outdated) linux system?

is there any reason why you cannot use a more current, normal server distro?

Thank you all for the help.

I understand that the server is very outdated ... but I can not update it.
we use it in a test layout, and we need to test it with the outdated server.

I'll compile the same kernel version on another server where there gcc and access to repositories.
And then try to compile the required modules.

Do you think there is a chance that the modules will work in the old server?

I believe the kernel and modules must be same build using the same gcc version. It might work if you build the kernel on that other machine, too.

I can't believe there's no support for that network device already available to you without building it out-of-tree. It's similar to the Intel pro/100 (e100) that I've been running since way back in 2.6.x times, in-tree (CONFIG_E1000) since forever. Simply installing the supporting binary package kernel modules for your system and kernel version (if you didn't already), modprobe it (e1000), and that should be enough. Many distros keep packages from old versions setting around. You can download those with whatever and then install the RPM (using --no-deps if needed) from the command line. IMO, you really don't need to go through all the build-from-source for the Intel support, gcc, nor the kernel. Did you try looking for it (locate e1000.ko) by name?