How to cite a paper as shortened first author name and year [Ste2002]? The way I'd like to cite papers in my work is 3 characters of the last name of the first author + year of publication without spaces, 'et al.' and comas.
I'd like to use Citavi, as it has convenient Word add-on, but I haven't found how to shorten last names there so far. After all, if it is possible in another program, I will give it a try.  

Such citing style was chosen to enhance reading experience, as reader can relate to the cited paper much easily by the last name and the year of publication and trace it throughout the document. This style is yet shorter, than patterns officially available in Citavi.
There's an easier LaTeX solution (compared to another answer):

\documentclass{article}
\begin{document}
\section{First section}

First statement \cite{gascuel97}, and a second statement \cite{sokal58}.

\bibliographystyle{alpha}  %Sets [Ste2002] bibligraphy style
\bibliography{sample}      %Imports bibliography file

\end{document}