I knew Roku couldn't solve this, was more curious about what other people have done.
As far as the overengineering, the Roku is one part of a much bigger puzzle here, and, much like my dev setup (
http://forums.roku.com/viewtopic.php?f=34&t=86102) seems excessive, it makes much more sense when you take into account some of the other things we have going on. The column idea you described I already do, just in a binary serialization format - without embedded field names like JSON or XML, I use positional fielding, but the end result is the same.
The Roku update thought was just wishful thinking, that I could pull a single web service call to my system, realize the Roku was out of date due to a versioning discrepancy, and trigger an channel update right there and then. Seems like it would be a simple thing for them to do as the Roku is perfectly capable of a midday update (system menu). Either a channel update or a full update, if that's the only way, would have prevented this from even being a question. So wasn't really "instant", so much as an on demand way to do something that would happen on it's own anyway.
The whole idea maybe is possible with ECP, but it isn't important enough to bother, and the menu structure isn't guaranteed to be stable in future updates (Home, Up, Right, Up...).
btw - CICS lol, next we'll have to support VMS, SSP, and 1401 Autocoder. You just dated yourself even knowing the acronym CICS existed.