Understand that my comments are just some "common sense with a little bit of physics" estimates, not direct knowledge of how best to shield laptops.
I'd do this in preference to worrying about what some 1978 government docs had to say about the subject. TEMPEST the specs are probably a mixture of "RF shielding" tips and standards, and a mix of Van Eck radiation tuner designs.
A long time ago I ran thermal measurement boards on a piece of equipment in liquid He under vacuum. Pretty icy. I used only standard components. My question is this - anyone know of any estimates of how weak a signal could be detected and actually rendered into useful information? The relevance of the low-T stuff is that it seems like a nice way to make low-noise receiving equipment. With an estimate of the capabilities of the receiver ( @exotic-lHe and commonplace-lN2 temps ) you could then address the emissions of the laptop with reasonable, quantitative target levels. Sort of reverse engineer the TEMPEST specs as it were. It would be nice to know what needed to be done to reduce emissions to the point that you could be fairly sure that an eavesdropper had to park on your doorstep to make his equipment work.
VERY FEW PEOPLE CARE ABOUT SECURITY.
Since they don't have anything to hide, why should they worry? Argh. ergo - if they're hiding something they are guilty of something. Bust the doors down boys. Mike