Database Software

Hi All
Earlier i started a thread about how to use and Excel spreadsheet as a source and i got an answer to follow a link where they asked me to modify the listener.ora file. I have couple of questions that i need help with.
1) If i modify the listener.ora file will there be any kind of impact on my existing OWB environment?
2) How do i modify it? I mean my listener.ora file looks like this:

copyright (c) 1997 by the Oracle Corporation
# 
# NAME
#   listener.ora
# FUNCTION
#   Network Listener startup parameter file example
# NOTES
#   This file contains all the parameters for listener.ora,
#   and could be used to configure the listener by uncommenting
#   and changing values.  Multiple listeners can be configured
#   in one listener.ora, so listener.ora parameters take the form
#   of SID_LIST_<lsnr>, where <lsnr> is the name of the listener
#   this parameter refers to.  All parameters and values are
#   case-insensitive.

# <lsnr>
#   This parameter specifies both the name of the listener, and
#   it listening address(es). Other parameters for this listener
#   us this name in place of <lsnr>.  When not specified,
#   the name for <lsnr> defaults to "LISTENER", with the default
#   address value as shown below.
#
# LISTENER =
#  (ADDRESS_LIST=
#	(ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1521))
#	(ADDRESS=(PROTOCOL=ipc)(KEY=PNPKEY)))	

# SID_LIST_<lsnr>
#   List of services the listener knows about and can connect 
#   clients to.  There is no default.  See the Net8 Administrator's
#   Guide for more information.
#
# SID_LIST_LISTENER=
#   (SID_LIST=
#	(SID_DESC=
#			#BEQUEATH CONFIG
#          (GLOBAL_DBNAME=salesdb.mycompany)
#          (SID_NAME=sid1)			
#          (ORACLE_HOME=/private/app/oracle/product/8.0.3)
#			#PRESPAWN CONFIG
#         (PRESPAWN_MAX=20)
#	  (PRESPAWN_LIST=
#           (PRESPAWN_DESC=(PROTOCOL=tcp)(POOL_SIZE=2)(TIMEOUT=1))
#         )
#        )
#       )
	
# PASSWORDS_<lsnr>
#   Specifies a password to authenticate stopping the listener.
#   Both encrypted and plain-text values can be set.  Encrypted passwords
#   can be set and stored using lsnrctl.  
#     LSNRCTL> change_password
#       Will prompt for old and new passwords, and use encryption both
#       to match the old password and to set the new one.
#     LSNRCTL> set password
#	Will prompt for the new password, for authentication with 
#       the listener. The password must be set before running the next
#       command.
#     LSNRCTL> save_config
#       Will save the changed password to listener.ora. These last two
#       steps are not necessary if SAVE_CONFIG_ON_STOP_<lsnr> is ON.
#       See below.
#
# Default: NONE
#
# PASSWORDS_LISTENER = 20A22647832FB454      # "foobar"

# SAVE_CONFIG_ON_STOP_<lsnr>
#   Tells the listener to save configuration changes to listener.ora when
#   it shuts down.  Changed parameter values will be written to the file,
#   while preserving formatting and comments.
# Default: OFF
# Values: ON/OFF
#
# SAVE_CONFIG_ON_STOP_LISTENER = ON

# USE_PLUG_AND_PLAY_<lsnr>
#   Tells the listener to contact an Onames server and register itself
#   and its services with Onames.
# Values: ON/OFF
# Default: OFF
#
# USE_PLUG_AND_PLAY_LISTENER = ON

# LOG_FILE_<lsnr>
#   Sets the name of the listener's log file.  The .log extension
#   is added automatically.
# Default=<lsnr>
#
# LOG_FILE_LISTENER = lsnr

# LOG_DIRECTORY_<lsnr>
#   Sets the directory for the listener's log file.
# Default: <oracle_home>/network/log
#
# LOG_DIRECTORY_LISTENER = /private/app/oracle/product/8.0.3/network/log

# TRACE_LEVEL_<lsnr>
#   Specifies desired tracing level.
# Default: OFF
# Values: OFF/USER/ADMIN/SUPPORT/0-16
#
# TRACE_LEVEL_LISTENER = SUPPORT

# TRACE_FILE_<lsnr>
#   Sets the name of the listener's trace file. The .trc extension
#   is added automatically.
# Default: <lsnr>
#
# TRACE_FILE_LISTENER = lsnr

# TRACE_DIRECTORY_<lsnr>
#   Sets the directory for the listener's trace file.
# Default: <oracle_home>/network/trace
#
# TRACE_DIRECTORY_LISTENER=/private/app/oracle/product/8.0.3/network/trace
# CONNECT_TIMEOUT_<lsnr>
#   Sets the number of seconds that the listener waits to get a 
#   valid database query after it has been started.
# Default: 10
#
# CONNECT_TIMEOUT_LISTENER=10

Where in the above file should i add the following code from the documentation?

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = excel)
      (ORACLE_HOME = C:\oracle11g\product\11.1.0\db_1)
      (PROGRAM = hsodbc)
    )
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oracle11g\product\11.1.0\db_1)
      (PROGRAM = extproc)
      )
  )

Thanks