I just wanted to add this for posterity in case anyone else struggles with this issue.
I just upgraded to 10.6.4/FCS3 from Tiger/FCP 6 and found my JL Cooper Spectrum was not controlling the 3Way CC.
It turns out FCP7's Timecode window (when open) interferes with The Spectrum (actually I use the Eclipse software) from addressing Universal Access to control the Color Corrector.
While the new low cost control surfaces that have come to market are tempting, having trackball control of FCP's color corrector is a very useful feature, at least for my workflow, which doesn't always allow for time to go into Color.
Hope this helps someone avoid the half a day lost to installing/reinstalling to try and fix this.