I have recently added instructions for adding SSH and FTP (using VSFTP instead of the FTP found here) to my blog at http://consumerelectronicshacker.blogspot.com and I wanted to share it here because I believe it will work more devices than just the ScreenPlay. The script to do the install will probably NOT work on other devices because it depends on the hard drive to be mounted at specific locations. But I've added enough comments in the script to indicate what is happening that anybody should be able to manually install.
VSFTP is way faster than the FTP already found here, so well worth checking out. I did SSH at the request of somebody else. It works well as a telnet replacement, but is much slower for file transfer.