XSkinMaker5.4.exe - use it for extract skins (old format)
XSkinMaker.exe for new skin format, just drop config.txt on it to make skin file or skin file to extract images and config.txt
Repacker.exe - if you click on it, it will search all *.smxd files, extract them and create new format *.xwd. You should copy repacker.exe, xskinmaker5.4.exe, xskinamker into directory where you have got your old skins (*.smxd) and just double click on repacker.exe :)

Enjoy. Likhonos Vladimir.