username = 'admin' (without the quotes) and is not configurable
password = defined in the DNASs sc_serv.ini configuration file (default section shown below):
; Password. While SHOUTcast never asks a listener for a password, a
; password is required to broadcast through the server, and to perform
; administration via the web interface to this server. This server should
; consist of only letters and numbers, and is the same server your broadcaster
; will need to enter in the SHOUTcast Source Plug-in for Winamp. THIS VALUE
; CANNOT BE BLANK.