Create a bootable Linux USB flash drive in puppy Linux manually without any app like UNetbootin

The Linux version of UNetbootin won't
run in Puppy because of missing
dependencies. But it is sometimes
possible to do the manual equivalent of
UNetbootin to convert a Linux distro's
ISO file into a bootable flash drive. Here
are the steps:
1. Mount the flash drive and delete
everything on it.
2. Unmount the flash drive but leave it
plugged in.
3. Determine the device name of your
flash drive. It may be sdb1 .
4. Open a terminal and type:
Code:
syslinux /dev/sdXY
where XY is your flash drive. Make sure
you get this right!
5. Mount the flash drive. You should see the file ldlinux.sys on it.
6. Click on the distro's ISO file to mount
it. Copy everything off the ISO onto the
flash drive. There may be some hidden
files, so use the ROX eyeball icon to see
them.
7. Does the ISO contain a folder named
isolinux ? It may be inside another folder
named boot. If so, copy all the files in
the isolinux folder to the root of the
flash drive.
8. You should now see a file named
isolinux.cfg at the root of the flash
drive. Rename it to syslinux.cfg .
9. If you cannot find an isolinux.cfg file
anywhere in the ISO, it may be using a
different bootloader. In that case, your
best bet is to manually create a file
named syslinux.cfg with the following
line
Code:
default /boot/vmlinuz
initrd=/boot/initrd.gz
vga=normal
10. Unmount everything and reboot off
the flash drive.

If it won't boot, here are some trouble-
shooting questions.
Do you know for sure that your machine
supports USB bootability? Many older
machines (and some newer ones) don't.
The best scenario is where the BIOS
detects the flash drive as a secondary
hard drive.
Have you modified your BIOS boot
priority list to enable USB booting?
Have you set the boot flag on the flash
drive partition? Check this with Gparted.
Does the MBR of your flash drive contain
the standard DOS/WIn boot code? If not,
you can manually update the code as
follows:
1. Locate the file mbr.bin in the folder /
usr/lib/syslinux .
2. Write this file onto the MBR of your
flash drive using a command like:
Code:
dd if=mbr.bin of=/dev/
sdb
Note that this command uses sdb and
not sdb1.

Source:
www.murga-linux.com/puppy/viewtopic.php?p=413412#413412