Jed's Half-Life Model Viewer is a great tool if you want to see each new CS1.6 model before installing it on game .Also this tool let you edit models textures so you can make a new models easily . I'll show you how to do it :
1.Download Jed's Half-Life Model Viewer
2.Run the viewer then from file -> load model ,choose model file you want to edit ,for example (cstrike\models\player\gsg9\gsg9.mdl)
3.Go to Textures panel then click "Export Texture" and save texture file .
4.Open the result file with your favorite image editor and change textures and colors as you want and save it as a new file with same extension "BMP".
5.From Textures panel click "Import Texture" and choose the new texture file .
6.From File menu click "Save Model as" and save the new model file .