It's probably not available via ppm because it can't be generated automatically because it fails its tests on Win32. The failures appear to be expected and should disappear if you set the environment as indicated in the error message, so you should be able to install it from source:

set TZ=PST8PDT
cpan Time::JulianDay
[download]

cpan should install any tool it needs. If not, you can get Visual Studio Express for free. (Click on "Visual C++ 2010 Express".)