Fortunately, there is an easy way to make Emacs ignore the embedded code entirely, by changing its syntax table to recognise @ as a single-line comment starter (like C++'s "//" comments). Add the following line to your c-mode-hook:
(modify-syntax-entry ?@ "< b")
The < in the syntax descriptor says that @ is now a comment starter, whilst the b means that it is a C++ style comment (it ends with a newline). Emacs will treat any text from @ until the end of the line as a comment, and won't attempt to format it as C code. (It is also smart enough to ignore instances of @ which appear inside double-quoted string constants.)
It's even possible to go a step further and have Emacs highlight @ lines differently from ordinary comments:
(font-lock-add-keywords 'c-mode '( ("^[ \\t]*\\(@\\)\\(.*\\)$" (1 font-lock-warning-face t nil) (2 font-lock-builtin-face t nil)))))
This will make the embedded code stand out, by highlighting the @ itself in a striking bold red, but displaying the embedded text in a more readable light steel blue (or whatever colours you've chosen for those standard faces).
6th February 2004