Unpacking GNS3 IOS binary images is accomplished using a few commands in the DOS prompt. My IOS images are stored in the folder C:\GNS3\IOS and that's the directory I will be referencing below. You should have at least one IOS image that ends with the .bin extension stored in your IOS folder. The process is the same no matter which IOS image you are unpacking. For this example I will be using c3660-jk9s-mz.124-15.T14.bin as my image.
The first step is to download the Cisco image unpacker 0.1 binary for Windows from GNS3.net. As of this writing it is the 3rd to last bullet in the Associated Software section towards the bottom of the page.
I like to save it directly to the C:\GNS3\IOS folder. Unzip it to the same location.
Open a command prompt and change directories to C:\GNS3\IOS.
cd C:\GNS3\IOS
I'm about to type in a command to run the unpack.exe executable that is located in the Unpack folder. I am running the command from the IOS folder so that the unpacked binary image will be located in the IOS folder when the command completes.
Type the following in the command prompt:
Unpack\unpack.exe --format IOS c3660-jk9s-mz.124-15.T14.bin
If all goes well you should receive a message stating the IOS image was successfully unpacked.
Type in dir to list the contents of the IOS folder and you should now see a .bin.unpacked file. This is the image file you want to load into your GNS3 IOS settings. One reason you want to do this is for your routers to load the image faster. The second reason is that eConfigs GNS3 labs are configured to run the unpacked IOS image. The eConfigs labs won't load properly on your GNS3 installation unless your IOS settings are pointing to the unpacked version of the image.
If you need to unpack ASA images you can check out the README.txt file in the Unpack folder for further instructions.