I just installed a Fr-Sky DIY kit into my (so far) faithful Spektrum DX7. I've kept the ability to use the stock DSM mode or switch that off and go to Fr-Sky on an additional antenna. (Installation based on info found here http://wiki.parkflyers.org.nz/wiki/index.php/DX7#FrSky_hack)
I took some photos on my cell phone at random intervals during the install. There's a limit of three attachments here, so I'll just link to the ParkFlyers.org.nz forum post with all 8 images included. http://www.parkflyers.org.nz/modules/newbb/viewtopic.php?topic_id=1420&post_id=24776#forumpost24776
Enjoy.