Dear Sandro,
the cygwin-1.7 can not install the package as
the Macaulay repository miss the setup-2.ini file.
The workaround is to install from a local directory.
You need to create on your "Local Package Directory"
a directory called
http%3a%2f%2fwww.math.uiuc.edu%2f
Then copy the file
http://www.math.uiuc.edu/Macaulay2/Repositories/cygwin/setup.ini
in it and rename it "setup-2.ini"
then create a subdirectory "Macaulay2"
and copy in it the package
http://www.math.uiuc.edu/Macaulay2/Repositories/cygwin/Macaulay2/Macaulay2-1.3.1-1.tar.bz2
In this way you have created the expected structure.
Now run setup-1.7 and choose "Install from Local Directory".
Regards
Marco