It is possible to make a bootable usb memory stick from a .iso file in OS X from the command line.
Converting the .iso file
After downloading the .iso file in terminal change to the directory with the .iso file and run the following command.
hdiutil convert -format UDRW -o filename_you_want.iso.img filename_you_downloaded.iso
after it is finished you will need to rename the output file because OS X makes it a .dmg file.
mv filename_you_want.iso.img.dmg filename_you_want.iso.img
Finding your mounted USB stick
From terminal run the command with the usb stick unplugged and the after plugging it in run the command again
In the list of devices from the second run there there should be a new device like /dev/disk2 and it may be a windows formatted usb stick.
Remember that the USB device you use will be erased and all data on it will be lost.
Assuming the usb stick is /dev/disk2 run the command.
diskutil unmountDisk /dev/disk2
to unmount the usb stick
Writing the image to the memory stick
You write the image file to the memory stick use the command
sudo dd if=filename_you_want.iso.img of=/dev/rdisk2 bs=1m
note: if= The input file the image file made from the .iso file.
of= The output file the device you are writing to. In this case we are using rdisk2 a raw device that should be a bit quicker that writing to disk2
bs=1m is block size 1 megabyte
It will take a few minutes to write the image the usb memory stick.