You need the "patch" program. You can get it if you install cygwin or probably from http://gnuwin32.sf.net ^*.

If you're talking about Tk-804.025_beta8.patch (the latest, available from nick's directory on cpan), this is what it says (hopefully it's self-explanatory)

# strip everything before this
# cd to your version of Tk-804.025_beta7
# and feed this file to /bin/sh
#
#
rm -f demos/demos/images/flower2.png
touch demos/demos/widget_lib/trace1.pl
chmod 0444 demos/demos/widget_lib/trace1.pl
touch PNG/libpng/scripts/makefile.mingw
chmod 0444 PNG/libpng/scripts/makefile.mingw
touch demos/demos/widget_lib/trace2.pl
chmod 0444 demos/demos/widget_lib/trace2.pl
touch demos/demos/widget_lib/choosedir.pl
chmod 0555 demos/demos/widget_lib/choosedir.pl
touch demos/demos/widget_lib/photo2.pl
chmod 0444 demos/demos/widget_lib/photo2.pl
patch -p1 -N <<'__END_OF_PATCH__'
...
[download]

patch --help describes the options

I quite often need to run ` chmod -R 0777 * ' in my Tk directory (cause I got cygwin) cause permissions get messed up (probably a bug in cygwin's tar).

update: the gnuwin32 route is a lot less massive than cygwin