Then when I manually ftp`d file to correct location, I couldn't really test site, cpanel gives you a temporary url xxx.xxx.xxx.xxx/~username where you can check site, but I couldnt do that with ispconfig (Ive probably missed something)
You can do this in ispconfig as well in asimilar way, see System > server config > web > website auto alias.
Btw, the plesk feature only works for very simple sites or plain html sites. You cant use it for compley cms systems that need a proper url path or use rewriting. So the only way thats 100% reliable is the way monkfish described.