cygport for simple package addon: skip prep?

[Heavenly Avenger]

I am trying to write a cygport file for an extension to docbook-xsl 
called mathml.

The latest version of the DTD file is at 
https://docbook.org/xml/mathml/${VERSION}/dbmathml.dtd, and it is not 
zipped nor packaged in any way.

The package consists on just a single .DTD file and I can't figure out 
how to make cygport "skip" the unpack attempt during "cygport prep". I 
might need to just copy the file into what it assumes to be the package 
directory, then during compile/install time, just copy over the file to 
the correct location, and determine that as the package's contents.

I have this debian package as a base to what should be in the package 
file: https://packages.debian.org/sid/all/docbook-mathml/filelist

It seems to be a so basic addition that cygport is kind of too complex 
for it -- but it would be useful as a way to "remember" installation 
steps required on cygwin, if the correct setup instructions are saved in 
a cygport file.

Any ideas and directions are welcome. If you know a cygwin package in a 
similar format (just installs a file that it downloads in its original, 
uncompressed format), that'd be of great help as well.

Thanks in advance!