How to add oneself to a ticket's CC field?

[David MacMahon]

I tried to find a way to add myself to a ticket's CC field, but  
couldn't figure it out.  Is it disabled or otherwise hidden?  I  
couldn't do much of anything to an existing ticket except add a  
comment and/or attach a file.

It would be nice if I could at least add/remove myself from the CC  
field.  Is that possible or is it a Trac permission granularity  
limitation?

Thanks,
Dave