Can you select the firewire drive in the Startup pref pane? If so, what happens whan you try to start up from it? Flashing ? mark?
I cloned 10.2.6 to my Firewire drive, and it shows up as a valid OS in the Startup pref pane, but I haven't actually tried booting from it, yet. 10.2.6 was a pretty minor update-- I don't think anything was added that should disrupt CCC's ability to clone the OS. Maybe try the clone again, and double-check that the "make bootable" option is checked in CCC prefs.
CV