I made modifications to this Python plugin to get it working. It came with the python plug-in package found at:http://python-fu.sourceforge.net/You can get the modified plugin below.
Usage: Install it in the GIMP plug-ins folder. Top two text input is for new file size - width, height. If you want to use pictures for the eyes, click yes, and type in the image names. While testing this I found that any image used must be in your default image folder for GIMP, leaving one image textbox blank produced errors. You must type out the full filename and extension of those images in both textboxes. You can use the same image for both eyes, just be sure to add the filename to both boxes.
Working on Vista 64 bit, Vista 32 bit, and XP on GIMP 2.6.7. I haven't tested it on Ubuntu, yet.