I have been working with John from http://www.chrysocome.net/dd and he
has prepared a very experimental 0.6beta2 version of dd that writes by
simply addressing the drive letter of your USB device.
http://webconverger.com/dd.exe
Assuming your USB stick comes up as the drive letter E:
1. Make sure the the selection of drive e
is working (look like it is but check against dd --list)
dd id=e: of=/dev/null
2. Try writing
dd if=mini.img od=e: