Invisible X11

[dem]

I recently upgraded from 10.2 to 10.4 as I require X11 for Matlab. I have a PowerBook G4, did a clean install and am on 10.4.2. I installed X11 from the disk (in initial install, and seperately through the X11 package), and installation was 'successful'. However there is no X11 folder, in Applications -> Utilities, or anywhere else. Downloading X11user- it won't install as I apparently already have X11. Matlab tells me I don't have it, and won't run.

Please help!

[dem]

A different approach - does anyone know if I can use the terminal to install this package?
That is, do you know of any tricky commands I can use to explicitly install this X11? (Rather than through the installer....)