kernel-source-2.4.22-30mdk.i586.rpm will install the kernel source in your /usr/src directory, ready for you to compile.
kernel-2.4.22.30mdk-1-1mdk.src.rpm if I'm not mistaken, will produce an rpm similar to kernel-source-2.4.22-30mdk.i586.rpm (depending on which if any complile flags you use) which you will then have to install.
In other words, wait for a more experienced user to explain lol.