[Bro] Changing separator

[James Lay]

So...I'm almost certain that there was a way to change from the tab 
character, to comma (I thought), but for the life of me I can't seem to 
find it.  Been working with logstash and currently messages come through 
as:

1382627138.211512\tCQ74U23HZlcab0LNnh\t192.168.1.3\t64079\t224.0.0.1\t8612\tudp\t-\t-\t-\t-\tS0\tT\t0\tD\t1\t44\t0\t0\t(empty)

Which is kind of painful for matching.  Any quick pointers on how to do 
this?  Thank you.

James