Citation style 'Text after' separator

[Sam Aaron]

Hi there,

when I add a citation in LyX (version 1.6.0) I get to choose some  
formatting options including entering text into the 'Text after'  
field. Any text entered here is then appended to the citation itself  
separated with a comma. Is there any way to change the separator to be  
a colon?

i.e. instead of:

[MindfulBody, 12-15]

I'd like to see:

[MindfulBody: 12-15]

Thanks in advance,

Sam Aaron