We run Ubuntu on a lot of the department computers, and some things are easier to configure via their appropriate GUI than they are from the command line (sigh, :p). I don't have to do this often, so often I don't remember the interface, or even the name, of the app required for the particular configuration I'm try adjust. Ah, I think, if I was only sitting in front of the computer in question rather than logging in via SSH, I could click on the Preferences dialog and it would be right there. Wait, why should it matter what computer I'm sitting in front of? Enter nested X servers such as Xnest and its successor Xephyr.
The problem with running a remote desktop or windows manager is that when you fire up your local X server, you usually also fire up a windows manager to manage it. If you try to run a remote windows manager, there will be two managers trying to manage one server, which can be problematic. Xephyr lets you start another X server nested inside a window of your main X server, and you can then start the remote windows manager in the Xephyr window. Basic usage looks like this:
home$ Xephyr :1 -ac -screen 800x600 2>/dev/null &
home$ export DISPLAY=:1
home$ ssh -YC hop1
hop1$ ssh -YC hop2
...
hopN$ ssh -YC target
target$ gnome-session
Don't forget to kill the Xephyr process once you're done with it.
Of course, with all the X forwarding, it doesn't actually matter which host Xephyr is running on. However, it may be easier for you if you only have to install it on your main computer. See Igor Ljubuncic's [Xephyr tutorial][] for a more detailed explanation of the whole process.
In order to install Xephyr on Gentoo, you'll need to (re-)emerge
x11-base/xorg-server
with the kdrive
USE
flag enabled.
[!tag tags/linux] [!tag tags/tools]