Yes, but you'll have to compile your own build with one change:
Open apps/main.c, and look for the line saying:
/*#define AUTOROCK*/ /* define this to check for "autostart.rock" on boot */Change that to
#define AUTOROCKand build. After installing, copy the plugin you want to a file called "autostart.rock" in the .rockbox directory
Alternatively, maybe you could just use a theme that shows the time in a big font?