Mine (340RL) is the same way. There were two screws holding in a panel in the back of a cabinet to the left of the refrigerator. I removed the panel and there is a residential style icemaker shutoff valve. It would appear that in order to get the line from the refrigerator, I will have to pull it out. I'm not keen on doing that, so I guess I won't be able to use the icemaker.
I can understand not hooking it up at the factory (I guess), but not sure why they didn't go ahead and feed the line in the same compartment as the valve when installing the fridge. There's already a hole there, because the power cord for the fridge runs into the same compartment as the residential ice maker valve.