By request, we've added support for custom player commands in the Ant task for version 4.1.0. We're still banging out the details of the 4.1.0 release, but if anyone wants to run the first draft of the support, check out the master branch for my flexunit fork at http://github.com/blegros/flexunit. The FlexUnit4SampleCIProject has been updated to show an example using the Flash-plugin for the browser as a custom command to execute a test suite. The support isn't limited however to the browser; any custom command can be provided and based on the value of the "player" property, it will attempt to execute the command using that player's style of invocation.
We're in the processing of updating the main flexunit project so that Hudson will start versioning, archiving, and fingerprinting artifacts for easier public consumption. Until then, the swc's and jar to work with the Ant task can be found in the sample CI project. Make sure to update both your flexunit-cilistener.swc and flexUnitTasks.jar (http://github.com/blegros/flexunit/tree/master/FlexUnit4SampleCIProject/libs/).
If anyone has any questions or finds any bugs, please don't hesitate to start up a thread on the forum.