Each time I have installed Solaris 8 I have always answered y to the question Is this machine networked (y/n): which then further prompts for Interface, Hostname, IP Address, subnet mask, etc. So I guess if you answer n, then no NIC is configured.
By editing the following files (or running sys-unconfig - see man pages before you do) you can achieve the same result.
vi /etc/hosts (enter IP Address & host name
vi /etc/hostname.xxn (where xxn is ce0 or hme0 or whatever, enter host name
vi /etc/netmasks (enter network-number & netmask
cat /etc/nodename (check it contains host name
I hope that helps you (and that I haven't forgotten a file).
Mike