REDSPEC is an IDL based reduction package that, although designed with NIRSPEC in mind, has also been used to reduce data from other spectrographs. It was written by the folks at the UCLA IR lab. You will need IDL version 5.3 or higher and the IDL astronomical users library.
If data are taken without motors initialized (e.g. after a server crash), SPATMAP will default to high resolution mode. If your data is in low resolution mode, you will have to add the FITS header keyword "ECHLPOS" with the value "179.7" to get SPATMAP to run properly.