asterisk users - Feb 2010 - moving a bridged call to a conference room

I'm just figuring out conferencing. I have a super-simple setup with one 
room:

exten => 600,1,Answer
exten => 600,2,ConfBridge(1234,c|M|s)
exten => 600,3,hangup

If two people want to take their (bridged) call to the conference room, 
the local user has to do a transfer (to 600), and then dial 600 themselves.

Is there an easier way to transfer both ends of a bridged call to the 
conference room?

- Mike