I learned this from someone on Yahoo Answers and modified it, and asked because I am tired of asking people to send me emoticons 50 times!
1) If using Windows, go to My Comptuer.
2) Tools> Folder Options> View Tab> Mark the circle under “Hidden files and folders” that says “Show hidden files and folders”. Click “Apply” and then “Ok”.
3) Go to C:\Documents and settings\”your user name”\Application Data\Microsoft\Msn Messenger\ and look for folders with weird number names. Depending on your version of MSN, your emoticons will be in one of those folders or a sub-folder named “CustomEmoticons”. Mine were in “C:\Documents and Settings\Sean Aune\Application Data\Microsoft\MSN Messenger\*folder with number name*\CustomEmoticons
4) You will see a lot of files with names like “0am2DD.dat”. All of the .dat files are your user added emoticons.
5) Copy all those .dat files to a new folder somewhere on your desktop, or anywhere that’s easy to get to.
6) Rename all of these to .gif. There are two ways to do this.
A) One at a time by clicking on them with your right mouse button and clicking on “rename” and changing “.dat” to “.gif”
B) Go to download.com and download this free program. Once installed, open it and click on the tab that says “Massive”. On the left, point to the folder where you put the files, and select it. Again on the right, in the “From” field type in .dat and in the “To” field enter .gif. Click “Rename”.
7) You now have all your emoticons as .gif files and you can take them to any computer with MSN and enter them. You will have to redo their Keyboard Shortcuts, but it’s a small price to pay as compared to losing all of them. Or you can just back them up somewhere safe.
Feel free to ask questions or for help.