Installing Puppy from an ISO
How to install Puppy to an HDD using Easy2Boot
You can boot directly from the ISO to a 'LiveCD' version of Puppy and get to the Desktop.
But if you then try to install Puppy to a hard disk, you may get an error because it cannot find the 'CDROM'.
First, if you have a CD drive, ensure it is empty.
Then use these commands in a terminal shell session before you start the Install process:
mount /dev/sdX4 /cdrom
where X is the letter for your E2B USB drive (in my case it was 'a' because I was using VBOX+VMUB).
The first command will probably fail if you have a CD-ROM drive fitted (make sure it's empty), but you can ignore the error.
This mounts the ISO as the CD-ROM so it can be found by the installer.