It is easy as plugging a Flash Drive to boot a Pendrive with Linux utlity called UNetbootIn.
It does the job in four steps and the it is a graphic and not command line utility.
1. download the Iso image
2. Extract and copy iso file
3. Install the boot loader called GRUB
4. Reboot and enjoy
Only a few Linux distributions are supported by this utility as at present and I use Puppy (100 MiB) for my work.
Remember DSL, Backtrack, PCLinux (not Knoppix) and a host of Linux distribution now can be mounted on a Pendrive.
This is just to let you know that I have booted Puppy Linux 4.2, the first of all the Puppies I used (now it is Puppy Lupu 5.2.5) on a Flash Drive and configured the internet and edited this page on seamonkey (while I am doing this see monkey is telling me a new version is available) web browser.
Puppy and UnetBootIn rocks the Linux World which is 20 years young.