Board Manager support for Windows and Linux version Arduino is now available. Add following line to File --> Preferences --> Additional Board Manager URLs:
It still need compiler, sparc-elf-3.4.4-mingw.zip, be manually installed under "c:\opt", or there will be compile error. We haven't figured out how to avoid manual install of this yet.
Existing 1.5.6 users already have this "c:\opt" contents do not need to reinstall.
Hope this make things easier when updating library !