I am only answering because you had no reply yet, I am not sure my thoughts can be of any help to you and I am not sure I understand what your problem is.
Syscalls evolve all the time, new ones are always added to the list. If you have RH9, it is unlikely this OS is ready for syscalls created after the introduction of RH9.
On the other hand, if you upgrade to a newer kernel as you have done, then the syscalls are automatically available with this new kernel and you do not need to do anything. However syscalls added to the 2.6 kernel will not be available to your 2.4 kernel.
Also, the syscalls that are regularly added to new kernels are specialised and programmers who make use of them have very specific reasons to do so.
A program that uses such calls will not work with a previous kernel.
In most programming, the old syscalls that were used 30 years ago are still used today.
If you are interested in assembly syscalls for Linux (also used in C and other languages), see:
I hope this helps.