You can do this by using a Trisquel's net-install ISO. Those ISO files are
specifically designed so you can either burn them to CD, or write them to an
USB stick. To write an net-install ISO to an USB stick, you can run the
following commands:
sudo dd if=trisquel-netinst_5.0_i686.iso of=/dev/sd#
sync
"/dev/sd#" is the device where you will write the image to. You must replace
"#" with the appropriate small Latin letter ("a", "b", "c", ...), so the name
corresponds to your USB stick. For example, the name could be "/dev/sdc". Be
careful to not mistake your USB stick with another device, because the above
command will delete everything on that device. You can see which device your
USB stick is in Disk Utility.
The "sync" command makes sure everything is written on the USB stick, so you
don't remove it prematurely.
