scrlttr2: Seitenzahlen in Brief formatieren

\documentclass[
	pagenumber=botright,
   enlargefirstpage=true
]{scrlttr2}
 
\usepackage[T1]{fontenc}
\usepackage[american]{babel}
\usepackage{blindtext}
\usepackage{calc}
 
\pagestyle{myheadings}
 
\begin{document}
  \setkomavar{fromname}{Adi Absender}
  \setkomavar{fromaddress}{Adi Absender's Absenderadresse}
  \setkomavar{fromphone}{+49 0123456789}
  \setkomavar{fromemail}{absender@nurzumspass.com}
  \setkomavar{fromurl}{http://www.nurzumspass.com}
  \setkomavar{place}{Spassstadt}
  \firsthead{% 
		\begin{minipage}[t]{0.5\textwidth}
			\vspace{0pt}
			\framebox[\textwidth]{\rule{0pt}{50pt}Adi Absender's logo}%
		\end{minipage}%
		\hfill%	
		\begin{minipage}[t]{\widthof{\usekomavar{fromurl}}}
			\vspace{0pt}
			{\sffamily\bfseries Spassdepartment}\\
			Spassoffice\\
			Spassofficeadresse
			\par\bigskip
			{\sffamily\bfseries Dr.\ \usekomavar{fromname}}\\
	      \usekomavar{fromphone}\\
	      \usekomavar{fromemail}\\
	      \usekomavar{fromurl}%
		\end{minipage}%
  }
  \begin{letter}{% 
	  Herr Blablubb\\
	  Blubberstrasse 17\\
	  0815 Blastadt% 
  }% 
  \setkomavar{date}{2011-08-01}
  \setkomavar{subject}{\sffamily\bfseries Sehr wichtig}
  \opening{Sehr geehrter Herr Blablubb,}
  		\blindtext\par\blindtext\par\blindtext\par\blindtext\par\blindtext\par\blindtext
  \closing{Mit der Ihnen geb\"uhrenden Hochachtung,}
  \setkomavar{signature}{\usekomavar{fromname}}
  \end{letter}
\end{document}