If you don't own the PC, do not *** with it. Tell the owner and have them change the screen
saver or live with it.
Or, just turn the screen saver off. It is there only to entertain you anyway.
I don't own the PC. I can't install programs but I know some of the
programs I can install on other machines and copy the code over and it
still works. So if I can find such a software, I can try installing
on another machine and copy the codes over.