I think the Apollo 630 has a jumper on it to wire in a disable switch, but there isn't one by default. Don't know about the 620, but I'd assume not.
I went the PCMCIA RAM route because as expensive as it is, it's still far cheaper and easier to find than an actual A600 accelerator. Safer, too, since there's no risk of the accelerator jumping off the inverted 68000 socket.