If you installed from CD-ROM, you should be able to do:
mount /mnt/cdrom
If you get an error that says the mount point does not exist, do:
mkdir /mnt/cdrom
If you did an install via NFS: You need to know what type of CD-ROM you have. The best way is to watch the boot messages as you reboot, or look at /var/adm/messages (more /var/adm/messages). You most likely have an IDE CD-ROM that will show up as /dev/hdc or /dev/hdd, or you have a Sound Blaster type that is /dev/sbpcd, or you have a SCSI that is /dev/scd0.
In any case, you can do the following:
mount -t iso9660 /dev/xxxx /mnt/cdrom
and substitute xxxx for YOUR device. You can then: cd /mnt/cdrom and then: ls and you will be looking at the contents of the CD-ROM.