Hello Tom,
This was working for me!
MacBook-Pro-van-Richard-4:director rmiddelburg$ ./director -repository jar:file:/Users/rmiddelburg/Downloads/SAP_Web_IDE_Local_Inst/updatesite.zip\!/ -installIU com.sap.webide.orionplugin.feature.feature.group -destination /Applications/SAPWebIDE/eclipse
Kind regards,
Richard