I got Mozilla working with the Linux DOC. The only issue is that I mounted the /usr/local directory on a remote NFS share; Mozilla was installed in the usual place under /usr/local/mozilla. You'll also need to find and install the dependent libraries such as GTK, GLIB, some X11 libs, etc. rpms that were targeted for RH 6.2 should work fine.
installing the libs onto the DOC + removing Opera yielded a net gain of space on the DOC, which is always good..
Loading and running Mozilla wasn't too bad- if you have a fast enough network and NFS server. Responsiveness is a bit sluggish, but managable. You get quite a bit more screen real-estate when you trim down the toolbar windows!
Are there any good 'lightweight' mozilla based browsers out there that could fit directly on the DOC?