I think it was possible in earlier versions (I don't want to "downgrade" to check it^^), but I'm not so sure. At least now it is not possible anymore.
Using the REST API is a pretty good idea, but it would be more convenient to be able to do it directly in eclipse^^
The main Problem of using another way to download the files is, you cannot use the eclipse plugin to commit the file to Guvnor because they are already in Guvnor. At least this is what the plugin says^^
But it's ok. For this reason you can use WebDav B-)
Thanks for your help:)