I have an older Camwood WR 408 that we purchased used some time back. It has a 5 position tool changer. It works very well. I want to add some positions so I can auto-change more tools. How do I access and modify the sub program that drives the changer.  I'm sure that if I can access it, I can modify it with a little help.

That will depend on how it is controlled, if Mach3 is in charge then the M6Start.m1s file in the Macro folder is your best bet.