This is Perl module SWF::Changer.
SWF::Changer installation is straightforward. If your CPAN shell is set up, you should just be able to do
% cpan SWF::Changer
Download it, unpack it, then build it as per the usual:
% perl Makefile.PL % make && make test
Then install it:
% make install
SWF::Changer documentation is available as in POD. So you can do:
% perldoc SWF::Changer
to read the documentation online with your favorite pager.