To install Porteus on a USB drive just extract or mount the porteus
ISO (Windows users can use 7-zip, Winrar or cdEmu for this), copy the
/boot and /porteus folders from the ISO to your USB drive, then launch
/boot/win_start_here.hta (Windows) or /boot/lin_start_here.sh (Linux)
and follow the instructions.

Porteus can also be installed to your
hard drive -- see the Installation Methods section on our forum, at
http://porteus.org/forum/viewforum.php?f=62

More detailed info can be found at /boot/docs/install.txt
