I don't think the USB spec supports any sort of shared access, even when using some sort of hub/spliiter, so I reckon this won't work. Remember, NTFS/FAT are not cluster-aware file systems, so you don't want mutliple hosts reading/writing to a shared USB key. The file system would corrupt very quickly.
The only major way I know of people overcoming this is through various USB-over-IP systems. I dealt with these licensing keys/FOBs a lot at a past company, and it's a royal pain to get around (luckily, most the manufacturers we were dealing with were moving away from fobs). We researched a similar scenario (where a VM was needing access to a USB device [fax modem]), and the only real solution seemed to ensuring that VM always ran on the specific host (otherwise manually plugging the USB into the other host(s).
In other words, a royal PITA. I wonder if anyone else out there has come up with any amazing solutions to this.
