Your question is not clear. If you want to modify config.asp file in order to change certain lines with different values, then you may do this:
@echo off
setlocal EnableDelayedExpansion
rem Define new values of desired variables
set newValue[USPSUserID]=5442321
set newValue[USPSPassword]=$$$$$$$$$
(for /F "tokens=1,2 delims==" %%a in (config.asp) do (
set "value=%%b"
if defined newValue[%%a] set value=!newValue[%%a]!
echo %%a=!value!
)) > newConfig.asp