You would put <%EM_Since_Day%>-<%EM_Since_Month%>-<%EM_Since_Year%> in your profile template. And of course swap the order or fomating to whatever you like, for example you could then have:
04:03:2002 or 14/12/2002
or 04 (day) 03 (month) 2002 (year) if you thought your readers needed the tip. (just kidding now)
I have just put this into EM master code, but it is untested. I will test it then add it to 2.0.1.