I've been using Gentoo on my Linux servers for the past several years, and it's a very nifty piece of software/distribution. Although compiling all the required packages can be a bit slow, the installation process is very well documented. I can testify that that installing Gentoo takes less than 24 hours, the working days for a basic system (including X windows) and the night to compile KDE. The other components, such as JDK, Apache, Tomcat (or Resin) take another hour or two.
Normally, it should be even quicker than that. The aforementioned figures are based on my latest experience installing Gentoo on a virtual PC on my Windows XP laptop using VMWare. Running Linux on my laptop allows testing software that runs comfortably only on Linux
As you might have guessed, I am extremely happy with the results. If you occasionally need to perform testing on a Linux server, I recommend running one with VMWare+Gentoo combination.