I got Mark's email this morning. I like what you are doing (fun stuff!) and would be glad to help in anyway I can.
First, let me say that my involvement in the AOL-TV project wasn't as long as most others on the project. I came in about 6 months before launch, and left not long after it hit the shelves. Also, I acted more as a liason between AOL and the software provider, Liberate. Most of the software development was already done when I came on board.
The incarnation of the box that was purchased in stores was running Liberate's set-top software package on top of VxWorks, an RTOS by WindRiver. There was indeed an internal Linux port to the box, but as far as I know, it was never released, as the box seemed to suffer a short-lived success. I cannot speak as to what AOL's plans were for migrating from VxWorks to Linux, but the fact that a Linux port was done leads me to believe that they were exploring their options.
Beyond that, I cannot give much technical details on porting issues, chipsets, and the like. I can contact another person who was on the team, and would be in more of a position to answer your questions. I will contact him today and ask his permission to either contact Mark directly or post to this list.