non free - supplies free licenses to developers of FOSS
caters for Linux, MacOSX and Windows with same look and feel
multiple interfaces GUI/non-GUI
Some hints on how to start:
1) decide which platform you want to target (see above)
2) find out which tool you want to use on that platform (see above / google is your friend)
3) get yourself a snapshot of the source as anonymous user
4) build installer (see above) … a topic TarballContents may help
5) ask on Mailinglist if you need help (e.g. target directories)
6) announce result on Mailinglist
7) party enjoy the praise