If it has the tools you need you should be OK. Just thinking back I don't think ext4 is that old, but I could be wrong. It will also include things like hal. I just did this install with a the System Rescue CD from March of last year. I believe the biggest issues you will have is old file system tools and you might experience packages that will not build due to the age of the kernel.
That said, you should consider using the System Rescue CD. It does the exact same thing as the Gentoo CD except you also can use X during your install and I prefer Firefox over links any day. Also, copy and paste from the handbook to the terminal can be handy.
you can get it here. The rescue Cd is also nice to have around because it lives up to its name.
First things first, but not necessarily in that order.
Apologies if I take a while to respond. I'm currently working on the dematerialization circuit for my blue box.