The sample status bar codes are just that, samples.
You can modify one of those or write your own.
To get a better understanding of this code, see the Status Bar Control Sequences of the Directory Opus manual.
It's quite possible you'll find what you're looking for in this thread on Status Bar codes.
The example Tanis has posted there is coincidentally not much different from the one I use.
Edit Note:
I don't think you can add a custom Status Bar Sequence to the default samples.
You could file a feature request though.
I save mine in a text file.
Good Luck,
Zippo