Some of the older GlowIcon packages on Aminet are compatible with the newicon.library.
The ColorIcons from OS3.5/3.9 are not compatible as the icon.library has been rewritten.
Unfortunately, there's real no way to tell which icon sets are really NewIcons until you download them as most users have come to associate GlowIcons as ColorIcons.
As far as installation of NewIcons goes IIRC, I think all you really need ClassAction for is for the NewIcons prefs. Simply copying newicon.library to LIBS: should at least let you use NewIcons.
