buildpkg allows to execute .builder scripts and pass extra parameters to them.
The simplest example of use is:

    buildpkg PACKAGE

where PACKAGE is a subdirectory in /usr/src/tgz/packages and there is a file
PACKAGE.builder in /usr/src/tgz/packages/PACKAGE. If you want to run this
script automatically (without any questions, using the defaults), use parameter
--auto, ie.:

    buildpkg --auto PACKAGE

If you want to see full output of ./configure, "make" and "make install", use
parameter --output:

    buildpkg --output PACKAGE

If you want to use parameter --auto and change the default values of variables
that are being set by functions yes_or_no, use parameter --scheme. See FAQ (2)
for more informations about it.
If you don't know what schemes are available for a package, type:

    buildpkg --help PACKAGE

Now, as you know (you do, right?) there are src.tgz archives that look like
this:

    # tar tzf mutt-1.4i.src.tgz
    usr/src/tgz/sources/mutt/
    usr/src/tgz/sources/mutt/mutt-1.4i.tar.gz
    usr/src/tgz/sources/mutt/mutt.1.pl
    usr/src/tgz/sources/mutt/mutt.builder
    usr/src/tgz/sources/mutt/package-info-manual
    usr/src/tgz/sources/mutt/package-info-manual-html
    usr/src/tgz/sources/mutt/package-files-manual
    usr/src/tgz/sources/mutt/package-files-manual-html
    usr/src/tgz/sources/mutt/package-info-changelog
    usr/src/tgz/sources/mutt/package-files-changelog
    usr/src/tgz/sources/mutt/scheme.no-ssl
    usr/src/tgz/sources/mutt/scheme.no-imap
    usr/src/tgz/sources/mutt/scheme.no-pop3

You can install a src.tgz archive in your /usr/src/tgz/sources tree, but you
can simply build a package directly from a src.tgz archive. Here is a reference
of options for managing the sources:

    buildpkg --install file.src.tgz

	installs source from a src.tgz archive

    buildpkg --remove package

	removes source of a package

    buildpkg --pack package

	packs source of a package into a src.tgz archive

    buildpkg [ --output ] [ --auto [ --scheme scheme ] ] --build file.src.tgz

	builds a package using src.tgz archive

.