The TV remote is read by the Arduino which activates the CM17A (wireless X10) which uses the house wiring to control lamps and switches.

www.youtube.com/watch?v=6TrnUZMg8ME

This demo uses boards created for a previous project.

Perhaps, what may be most helpful as an idea to others, is that all the fonts (127) and messages (30 or more  40 char strings) for the matrix are stored in a I2C EEPROM. (separately loaded with other sketches.) The fonts and messages are pulled from EEPROM by the working sketch as they are needed.

(The scrolling speed is still as fast as you'd want, and this sketch was only 9270 bytes.)