I define in my code additional reference commands,
\newcommand{\eqnref}{ \eqnrefname~\ref{eqn:#1} }%
\newcommand{\figref}{ \figurename~\ref{fig:#1} }%
\newcommand{\tabref}{ \tabrefname~\ref{tab:#1} }%
\newcommand{\secref}{ \secrefname~\ref{sec:#1} }%
which I would like to be recognised by tmx such that the auto completion
feature is applied for these as well.

Where can I add these (without changing the c++-sources)?