Riguardando il pacchetto classicthesis.sty ho trovato questa parte di codice:
% ********************************************************************
% headlines
% ********************************************************************
\PassOptionsToPackage{automark}{scrpage2}
\RequirePackage{scrpage2} % provides headers and footers (KOMA Script)
\clearscrheadings
\setheadsepline{0pt}
\ifthenelse{\boolean{@nochapters}}%
{\relax}%
{\renewcommand{\chaptermark}[1]{\markboth{\spacedlowsmallcaps{#1}}{\spacedlowsmallcaps{#1}}}}
\renewcommand{\sectionmark}[1]{\markright{\thesection\enspace\spacedlowsmallcaps{#1}}}
\lehead{\mbox{\llap{\small\thepage\kern2em}\headmark\hfil}}
\rohead{\mbox{\hfil{\headmark}\rlap{\small\kern2em\thepage}}}
% \renewcommand{\headfont}{\small}
\renewcommand{\headfont}{\small}
% \DeclareRobustCommand{\fixBothHeadlines}[2]{} % <--- ToDo
% hack to get the content headlines right (thanks, Lorenzo!)
\def\toc@heading{%
\ifthenelse{\boolean{@nochapters}}%
{\section*{\contentsname}}%nochapters
{\chapter*{\contentsname}}%chapters
\@mkboth{\spacedlowsmallcaps{\contentsname}}{\spacedlowsmallcaps{\contentsname}}}
C'è un modo per intervenire a questo livello? Ho provato con una cosa del genere
\lehead{\mbox{\includegraphics[scale=0.25]{3BP.jpg}}}
ma non ottengo alcun risultato.
Usando il pacchetto fancyhdr latex invece va in errore dicendo che i comandi \chead e \cfoot sono già definiti.