Not to my knowledge. If you Google there are vague hints that people have hacked the monitors in the 68k-era AIO Macs to support 800x600 at a very low (think eye-burn) refresh rate, but a quick look failed to turn up any instructions. (My guess is that it would a similar process to hacking a CC from 512x384, IE, modding the wiring harness to change the sense line information and futzing with a few resistor values in the monitor to permanently change it to the new fixed resolution.)