Had the same question today myself. You have to press and hold the little button on the front of the X2e for 3-5 seconds. That will enable the web interface for 5 minutes.
I believe the X2 (not X2e) has no web interface as to keep cost low and free up memory for SmartEngery, that code had to be removed from the firmware.
As rpugel says, on the X2e one enables the web interface for a few minutes only by pressing the button. This is more of a security issue, since if a home-owner had an ‘open’ wireless access point, this prevents a neighbor from fiddling with either neighbors Smart-Energy link to the utility.