The following tools and utilities are necessary for fully installing the OCCN package (version 3.0 beta. (Notice that external vcd viewing tools, such as gtkwave may also be helpful.)
gcc compiler 4.1.2
grace 5.1.22 (works with earlier versions too, e.g. 5.1.13)
Before proceeding to installation, please also read the details in INSTALL.txt available in the tar.gz archive.