If you have a Windows machine with VS2008, .Net 3.5, svn and patch on it, you can get the source for Witty here [1] and a patch [2] that will make it run against Identi.ca
Enjoy!
[1] http://code.google.com/p/wittytwitter/source/checkout
[2] http://code.google.com/p/wittytwitter/issues/detail?id=147