I tried to install 2006.1 with the graphical interface - after following the 17 steps for installation everything started and hang after 2 hours when emerge wanted me to manually download the java-API-doc.zip-file from SUN.
Is it possible to add a package-checking feature beforing starting the installation so that the graphical installer gives you a list of needed files before start. So I were able to download these files and put them somewhere. The installation itself could then proceed without interruption.
Another possibility to solve this problem is a more interactive graphical installer which stops the emerge and gives you the chance to hit "Retry" after you downloaded the files manually.
It's not possible to know beforehand if a certain package has a fetch restriction. It's also not feasible to make the install interactive. The installer isn't designed that way.