Here are some things that have worked for me with creating a live Linux USB stick in Linux. I have also been able to remove the U3 Launchpad from my usb stick using these tools.

If your USB stick is already properly partitioned then you can simply give usb-creator-gtk a try.

If that works then you are all done. For those of us who are not so fortunate, we will need to format and create a fresh partition in order to setup a bootable Live Linux USB stick.

fdisk can come in handy for formatting your usb stick


sudo fdisk /dev/sdb (make sure you have the correct path to your usb stick you
don't want to end up formatting your hard drive)

Once you have opened fdisk and used the /dev/ command to point it to your 
usb drive you will need to press the letter d and press enter

Next you will need to press the number 1 for the partition number and enter.

Press N for new partition and hit enter.

Press W to write the partition and hit enter.

That should do the trick however in some cases I have used Gparted to 
delete and create new partitions on the usb drive.