\@title and \@author are technically only defined once you use \title and \author:
\def\title#1{\gdef\@title{#1}}
\def\@title{\@latex@error{No \noexpand\title given}\@ehc}
\def\author#1{\gdef\@author{#1}}
\def\@author{\@latex@warning@no@line{No \noexpand\author given}}
That is, if you reference \@title and/or \@author without calling \title and \author first, it should produce a warning. To avoid this situation, based on the fact that you're writing a special class, you could use a different approach:
\let\@title\@empty
\let\@author\@empty
\fancyfoot[C]{\ifx\@author\@empty\else\@author~--~\fi\ifx\@title\@empty\else\@title\fi}
The above sets the footer to be AUTHOR - TITLE if both are defined. It will only be TITLE if no author is defined. It can be expanded to properly work if an author is given but no title.
Here's a minimal example using lipsum and fancyhdr:

\documentclass{article}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{fancyhdr}% http://ctan.org/pkg/fancyhdr
\makeatletter
\fancyfoot{}
\fancyfoot[C]{\ifx\@author\@empty\else\@author~--~\fi\ifx\@title\@empty\else\@title\fi}
\let\@title\@empty
\let\@author\@empty
\makeatother
\title{My title}
\author{Me}
\pagestyle{fancy}%
\begin{document}
\lipsum[1-3]
\end{document}
If you're actually using \maketitle as well, you need a little more work done. The MWE below adds \@@title and \@@author instead of \@title and \@author:
\documentclass{article}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{fancyhdr}% http://ctan.org/pkg/fancyhdr
\makeatletter
\def\title#1{\gdef\@title{#1}\gdef\@@title{#1}}
\def\author#1{\gdef\@author{#1}\gdef\@@author{#1}}
\let\@@title\@empty
\let\@@author\@empty
\fancyfoot{}
\fancyfoot[C]{\ifx\@@author\@empty\else\@@author~--~\fi\ifx\@@title\@empty\else\@@title\fi}
\title{My title}
\author{Me}
\begin{document}
\maketitle
\thispagestyle{fancy}%
\lipsum[1-3]
\end{document}
\titleand\authorthat redefines the values of\@titleand\@author, used when issuing\maketitle. Perhaps you can elaborate more on what you mean by "access the title and author". – Werner Jun 27 '12 at 23:28.clsfile,\fancyfoot[C]{AUTHOR—TITLE}, for example. I tried using\@titleand@authorthere but when I run pdflatex, the footer is simply—. – mk12 Jun 27 '12 at 23:31