The \mathcal
version defined by mathpazo
is given by
\DeclareSymbolFont{symbols}{OMS}{zplm}{m}{n}
\SetSymbolFont{symbols}{bold}{OMS}{zplm}{b}{n}
\DeclareSymbolFontAlphabet{\mathcal}{symbols}
These and other math fonts definitions are of course overwritten by the ones of eulervm
, so the only thing mathpazo
is doing there is using a Palatino font for text. (For that you might want to switch to TeX Gyre Pagella or New PX, but that's a matter of taste.)
If you don't mind wasting a math alphabet you can adapt the lines given above to something like
\documentclass{article}
\usepackage{mathpazo}
\usepackage{eulervm}
\DeclareMathAlphabet{\mathpazocal}{OMS}{zplm}{m}{n}
\SetMathAlphabet{\mathpazocal}{bold}{OMS}{zplm}{b}{n}
\begin{document}
% eulervm version
$\mathcal{ABCDE}$ {\boldmath$\mathcal{ABCDE}$}
% mathpazo version for one single symbol
$\mathpazocal{ABCDE}$ {\boldmath$\mathpazocal{ABCDE}$}
% make them synonyms
\DeclareRobustCommand*{\mathcal}[1]{\mathpazocal{#1}}
$\mathcal{ABCDE}$ {\boldmath$\mathcal{ABCDE}$}
\end{document}
