[horde] Global categories

[Ed Form]

Iasked about system-wide categories a few days ago and Jan Schneider was 
good enough to answer with...

 > You can set default values for category names and colors
 > in horde/config/prefs.php.

I've looked at this and can't see where or in what form I would do this. 
Can anyone suggest an example? For example I want to add a category 'Key 
dates' and colour it '#d11b00'

Ed Form