The environment I use when I have to use windows is Cygwin. This would probably be the best option if you wanted most of a bash shell available.
But this should be possible using a windows shell. Give me a few minutes and I’ll get you and answer (or at least a batch script).
Basically, what @heckflosse already posted. You can do this:
FOR %a IN (*.PEF) DO dcraw.exe -w -T %a