I've checked out master from the flashrom svn repo, compiled, and was able to see my chip (MX25L25635E).  The id wasn't recognized, but after a quick patch to copy a MX25L128... to ..L256.., I got it to successfully read the first 16MB of the chip - however, I can't get any further than that, because changing the values in the table to the right values moves me from 3 byte addressing to 4 byte addressing territory (if I understand this correctly), and it looks like there aren't any patches merged for that yet.