You can keep the files in the root of the trunk folder and if you want it to put all the files in the trunk folder into a subfolder you can set the "lotroi:dirname" svn property on the trunk directory. This will force the packager to put all the files in /trunk into a folder with the name you specified.
Was that what you were having trouble with?
lotroi:dirname property doesn't appear to do anything. :/
