Download the Linux install file. See Download Links. Download the "SIMetrix 5.x for Linux" file. If you don't have the required user name and password, click here
If not already, become root
cd to the directory where the downloaded file is located
Extract the files from the tar ball with (replace file name as appropriate):
tar zxf simetrix-5.5.tar.gz
Move the simetrix.tar and lib_extra.tar files to /usr/local