Running
qvm-features <vmname> stubdom-qrexec 1
in a dom0 terminal will allow usb devices to be attached to the qube, regardless of it there are tools installed it it.
If you have a usb drive, you could use it, otherwise this comment details how to mount a file from another qube as a block device:
I believe you will still need to run the above command for this to work.
I also remember reading a thread about mounting the root volume of one qube as a block device on another, but i can’t seem to find that one.