Well, on second thought, it’s actually more complicated than that. The /cp command:
(page 8) actually requires providing the entire list of program parameters, and the enable bit is part of the ‘flag’ byte. I agree this is not really user friendly, and it remained this way due to backward compatibility issues. It is, however, be pretty easy to modify the firmware slightly to introduce a new command, say /ep, dedicated to enable or disable the enable bit of a program.