Problem with username format

Hi!

I'm trying to use usernames, which are in MAC-address format (for example
00:02:9b:05:10:02). I added the colon to the username chars in 
raddb/config -file. It still doesn't work.  Radius.log gives the 
following information concerning this username:

Main.error: /usr/local/etc/raddb/users:19: parse error
Main.error: discarding user `00'

And when Radius receives the authreq with username 00:02:9b:05:10:02, it
is of course invalid.

It seems that Radius somehow splits the username at the first colon. What 
should I write to the radius.config? 

I'm using GNU Radius version 1.1.

Thanks!

Olli K.