GEIS may be obtained from either http://www.psychonomic.org/ARCHIVE/ or more recent versions from http://www.sourceforge.net. The file is called GEIS-<version>.ZIP, where `version' refers to the current version number.
Begin by uncompressing the file using an appropriate program. Extract the contents of the file to C:. You should now have the directories: C:\GEIS\BIN\, C:\GEIS\DOC\, and C:\GEIS\ETC\, as well as various subdirectories.