For the i386.rpm file do the following, download it and type in your favorite console:

'rpm -i netstat-nat-x.y.z.i386.rpm'

Or if you have a src.rpm file type:

'rpmbuild --rebuild --target=<CPU> netstat-nat-x.y.z.src.rpm'

and go into your freshly build rpm directory (exmpl. /usr/src/redhat/RPMS/<CPU> and install it as a normal RPM.

That's all.