1) Make a totally independant temporary folder (eg: C:\myemoticons)
2) Copy every .DAT, .DT2, (and .PNG) from
"\Documents and Settings\<windows accountname>\Application Data\Microsoft\MSN Messenger\<ID number>\"
and
"%userprofile%\Local Settings\Application Data\Microsoft\Messenger\<.NET passport>\ObjectStore\CustomEmoticons"
to that temporary folder
3) Remove both messenger directories
4) Go to your temporary folder with all the copied files and rename every single file to .PNG (if they aren't already named liked that)
5) remove duplicates images if you have some (check with an image viewer)
6) start Windows Live Messenger and start adding the icons in the proper way by going to Tools > Emoticons > Create... > Find Image
7) remove your temporary folder
Edit:
Custom emoticons problem?
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