Let me explain a couple things before my question...I am running Ubuntu from my flash drive because my hard drive crashed and I am waiting on some parts to come in. Since i cannot install Ubuntu onto the hard drive it makes it a real pain to install adobe flash. What I am wondering is it possible to take the flash.so file and put it into the files that the USB drive uses to run Ubuntu, so in other words I install flash and it works when the computer boots up and I launch firefox.
My understanding is that when creating a USB drive with Ubuntu's Live USB Creator application, it is possible to reserve some space to store data and packages installed "on top" of the ISO image. I.e. chances are all you need to do is actually install flash while booted from your USB drive.
See Ubuntu wiki for details.
In case your USB drive was created without this option (i.e. something like "discard changes on shutdown" has been chosen) - I'm afraid the easiest would be to re-create the drive, because it's basically an ISO filesystem (i.e. a CD image) and it's not supposed to be written to once created.