Download and unzip ymm.zip files
Go to Yahoo multi messenger folder.
Run yahoo multi messenger registry file and all is done
All you have to do is to open your yahoo messenger as usually. (If you have yahoo have Yahoo messenger open, click on his shortcut to open it again)
You can open it over and over again
Works for all versions of yahoo messnger.
To uninstall yahoo multi messenger run uninstall yahoo multi messenger.