This Google-cached article probably holds the key. If you're lucky. (Shorthand: Install the precompiled Xetc 'base package' if it's available, and/or just extract the rgb.txt from it without littering your slice with the rest.)
I'd kind of expect the file to reside *somewhere* in their CVS, allowing for a quick CVSweb download and no trouble, but I'm not finding it. (Not familiar enough with X11, perhaps... Why the heck would it have to be generated on the fly, if it is?)
