CC Mode should work out of the box with Emacs >= 20.4, and XEmacs >= 21.4. Emacs 19.34 and XEmacs 19.15 are no longer supported, since CC Mode now uses the syntax-table text property, which first appeared in Emacs 20.1 and XEmacs 21.4.

As of December 1 2005, Subword Minor Mode doesn't (yet) work in Emacs 20.n.

If you are going to be editing AWK buffers, note that your (X)Emacs might be configured to use the older AWK Mode (in the file awk-mode.elc) supplied with that (X)Emacs. The file README in the CC Mode distribution tells you how to configure your (X)Emacs to use CC Mode for AWK buffers.

If you're using Emacs 21.3 or earlier, or XEmacs 21.3 or earlier, then the file cc-fix.el(c) is needed and will be loaded automatically. It corrects for some bugs in those versions, and also contains compatibility glue for missing functions in older versions. cc-fix.el(c) is not needed for later versions.