I installed the processor.prefpane correctly and it shows up in my syspref and menu bar, but I can't change the cores to any other than the standard 8 my machine has. I'm thinking I have an old version of the processor.prefpane because it's telling me I have a "Intel Pentium III Processor" when I really have a Quad-core Intel Xeon, running Leopard 10.5.8. Here's a screenshot:
