You can replace stock init file (a program that starts all other programs, more or less) with a shell script which would first start VNC server, and then original init. AC/DC info is in one of files in /proc. The trouble is that one of init's jobs is to mount /proc (and music partitions). However, people were doing such things before (performing necessary mounts etc themselfes). Search the board a bit for custom init scripts (or wait untill somebody more knowledgeable chirps in here )