All my miggies have switches on the back (leading to the according jumper) for selecting PAL/NTSC - just toggle & reboot. Yes, this can also be done when powered up, the effect is on reboot only, however.
Ditto on my machines, accept I have mine on front.
I also have a 68030/68000 switch on the front. However watch out not all accelerators allow for toggling when powered up. example: Toggling the Fusion Forty (68040/68000) will damage the accelerator card and the a2000.
