In linux do:

mkfs.msdos -C floppy.flp 1440

# mount it

mkdir floppy

sudo mount -o loop floopy.flp floppy

cp <what_you_need_on_floppy> floppy/

sudo umount floppy

Once you have created the image copy it up to your datastore and then point your VM floppy drive at it.

This was so I can provide an SBS2011 Migration answer file to a VM.