The file ltxdoc.cfg can be used to customise some aspects of the
behaviour of the ltxdoc class; this class is used to typeset
the documented code in the .dtx files. If this file is present then
it is read in at the beginning of the file ltxdoc.cls.
As this file is read before the article class is loaded, you
may pass options to article. For example the following line
might be added to ltxdoc.cfg to format the documentation for A4 paper
instead of the default US letter paper size.
\PassOptionsToClass{a4paper}{article}
You should note however, that even if paper size options are specified,
the ltxdoc class always sets the \textwidth parameter to
355pt, to enable 72 columns of text to appear in the verbatim code
listings. If you really need to over-ride this you could use:
\AtEndOfClass{\setlength{\textwidth}{ ...}}
To set the \textwidth to your desired value at the end of the
ltxdoc class.
By default, most of the .dtx documented code files in the
distribution will produce a `description' section followed by full
source listing of the package. If you wish to suppress the source
listings you may add the following line to ltxdoc.cfg:
\AtBeginDocument{\OnlyDescription}
The documentation of the ltxdoc package, which may be typeset
from the file ltxdoc.dtx, contains more examples of the use of this
configuration file.