換個方式到 Google 搜尋，找到底下這篇，原來現在藏在這裡～～太久沒裝 X11 了～～哈哈～～
http://occy.net/node/166
注意：其實不用【前往檔案夾】，直接打開安裝光碟片上的 System / Installation 就會找到了！If you want to install X11, you have to do either of the following AFTER you install your Disc 1 cd:
1. Use "Go to folder method"
You'll have the window open when you insert the CD. simply do:
(from apple menu bar: Go >> Go to folder >> (type in: System) >> and then browse to Installation >> Packages >> and double click on: X11User.pkg
the second method...
2. From command line.
For this method, you'll need to have your cd in, and then simply:
cd /Volumes/Mac\ OS\ X\ Install\ Disc\ 1/System/Installation/Packages/
from that directory type: open .
It will open a new window for you. Double click on the X11User.pkg !
Enjoy!