If you are upgrading a non-production firewall, the step is much straight forward,
Copy the upgrade ISO into USB stick. Plug in your USB stick and mount it to use.
you can use the command /etc/dmesg to find out what is the drive your USB has been assigned. etc sda1, sdb1
Mount the USB with the following command:
mount /dev/sbd1 /mnt/usb
Change directory to your USB drive by:
cd /mnt/usb and locate for your ISO file.
Mount the ISO file as your cdrom.
mount -o loop Check_point_R75.20_Smart_1.iso /dev/cdrom
and issue the command:
"patch add cd" to initiate the upgrading process