\documentclass{article}

\makeatletter
\newcommand*{\CC}{%
  \begingroup
    \ifmmode
      \mbox{\fontfamily{fxl21}\fontencoding{U}\selectfont\char2}%
    \else
      \fontfamily{fxl21}\fontencoding{U}\selectfont\char2
    \fi
  \endgroup
}
\makeatother

\begin{document}

This is Computer Modern with \CC\ from Linux Libertine.

\end{document}