Hi Thiago,
You have to give the path to the webIDE local installation zip file not to the eclipse path.
ex.
director -repository jar:file:/C:\Midhun\Software\WebIDE\updatesite.zip!/ -installIU com.sap.webide.orionplugin.feature.feature.group -destination c:\SAPWebIDE\eclipse
Regards, Midhun
SAP Customer Experience Group - CEG