I need to ability to force the PDF output to be black & white. So I need it to override any colors specified in the CSS because I can't change those for another purpose. Is there a way in code to flag that option?

Thanks

No, there isn't an option for this. You could apply another style sheet to override the color:

* {
    color: black !important;
    background: transparent !important
}

However, this will not affect color images.

I remember reading that ghostscript can do this sort of operation - probably worth some research