I have written something like 2 batch scripts in my life, but here's how to take input from the command line:
script.bat filepath find replace
%1 = filepath, %2 = find, %3 = replace
To do replacement, do something like:
for /f "tokens=1,* delims=]" %%A in ('"type %1|find /n /v """') do (
set "line=%%B"
if defined line (
call set "line=echo.%%line:%~2=%~3%%"
for /f "delims=" %%X in ('"echo."%%line%%""') do %%~X
) ELSE echo.
)
(taken directly from the link posted by @russ, with the variable numbers changed.)
I think this should work for you.