You can go
HERE and download kernel-smp-2.4.22-1.2115.nptl.i686.rpm or kernel-smp-2.4.22-1.2115.nptl.athlon.rpm and try installing it as a rpm. Back then you would also want to download kernel-source-2.4.22-1.2115.nptl.i386.rpm if you wanted to compile any applications or anything. But Core 3 doesn't have the kernel source any more, so I don't know if kernel-source would load anymore. So, try this at your own risk.
That is a kernel from Fedora Core 1, I don't know if this will work with Core 3 or not. Core 3 has a much newer version of the GCC compiler, and glib, and just about everything else.
If you're not afraid of trashing your Core 3 installation, you can give it a try and see what happens. If you absolutely need that application, and the application needs that kernel, you might have to run the app in Fedora Core 1.
Pudge