"Whaaaat?" you say, "dispcal works just fine with the W701's built-in calibrator under Linux." Well, it should...
Problem is, the BIOS shuts off the LCD when you close the lid. I've not found a user-exposed LCD or backlight control in Linux, sysfs or otherwise, that does a gosh-darned thing when the lid is closed. I'm not aware of anyone else who's found one either. If someone out there knows of an existing software interface, please let me know!
Until I find the 'correct' software solution, there's an easy hack to make it work:
The W701's lid sensor is on the status led board to the right of the suspend indicator. A stainless steel ruler placed between the hinges blocks the magnet in the base, preventing the lid switch from turning off the LCD. TADA! Dispcal et. al. can do their magic.
(Aluminum and austenitic stainless steel won't work. A magnet has to stick to it. Fortunately the cheapy stainless rulers sold by e.g. Staples and Michaels fit the bill nicely.)