You can do it with Mac OS X from a terminal window like this:
# unzip dban-1.0.6_i386.exe
# dd if=dban-1.0.6_i386.IMA of=/dev/diskX bs=1k
If you do not have the `unzip` program available at the terminal prompt, then use any other program from the GUI. The EXE file is just a regular ZIP file with a special header for Microsoft Windows.
Change "diskX" to the device name of your floppy drive. Get this name right because you could accidentally overwrite a hard drive.
A good way to get the right floppy drive device name is to run `mount` at the prompt, insert a formatted floppy disk, run `mount` again, and compare the difference.