I am quite new to beamerposter, but eager to take a chance to try it. There are conferences (e.g. CVPR) that requires poster to be 3 times an A0 size. I'm wondering if there's a natural way (supported way) to do it with beamerposter class? Or should I just go with A0 size and somehow zoom it up during printing?
With the size=custom
key you can select the paper size manually.
(the numbers below are just dummy values, you'll have to look up the correct values)
\documentclass{beamer}
\usepackage[size=custom,width=77,height=107,scale=1.4]{beamerposter}
\begin{document}
\begin{frame}
abc
\end{frame}
\end{document}