How to manage affinity for cpu cores of quad core proc in Slackware/Linux?

Hello, I searched in google more about cpu core utilization and affinity, but the information I found is not I want. I have Xeon quad core proc and I want to tell the kernel to use 2 cores for all processes by default and to let me set the other two for a special process as apache, mysql or virtual machine. For example: 2 cores for everything, 1 core for vmware VM, 1 core for another vmware VM. Can somebody suggest a strategy for making this possible. Thank you.