The hummy is linux-based. It can read NTFS partitions, but not write to them. It can read and write to FAT32, but FAT32 has a filesize limit of 4GB, so beware. The hummy's native file system is ext3, which it can read or write with no restrictions.
The hummy can format your external drive in ext3, but it can only format the whole drive, not a partition. No one said it was supposed to be easy....
Believe me, the simplest solution is to install the virtual disk. You can then copy the file(s) you want to virtual and from there to your pc using either ftp or the OPT+ button in the "Browse Media Files" option in the web interface.