Ok, update, I did not have VirtualBox Extensions installed, which you need to be able to enable USB 2.0. When I did that, and had both USB boxes checked, I succeeded in attaching the fastbooted Kindle to virtualbox! It is listed as being attached when I hover over the USB icon. However... still "<waiting for device>" And it appears to drop out of fastboot (or at least detach) in about 5 minutes. I am using the fastboot binary that was posted earlier in this thread, and I am in a very low battery (doesn't seem to be any way out of that, since it only seems to charge in "please plug me in" mode, but that amount of charge gives me a little bit of time).
Last edited by Poetcop; 03-10-2012 at 06:37 PM.