You might find the icons at Linspire's source code ftp site:
ftp://130.94.123.237
You can download the iso of all the sources for Linspire 5.0, or browse individual packages for Linspire 4.5.
In Linspire 4.5, the icons can be found in:
lindows-crystal_1.0.0-lindows24.tar.gz
In lindows-crystal/usr/share/icons/Lindows-Crystal/copying, it says the whole package is under LGPL, so I think the icons are free.
I totally agree - KDE should incorporate the best Linspire icons. Particularly, the green "Click 'N Run" button would make a good icon for the "Run Command..." option in Kmenu - the icon of a person running is more intuitive than the current gear icon.