batch editing midi files

Does anyone have a clever method for batch editing midi files or know of some software that can help?

The problem seems simple, I have a few hundred midi files that I use as backing tracks for live performance and I've mixed them to suit my current sound module. I get a new sound module and for example want to use a different bass guitar and reduce the volume on the drum channel across all my files. At the moment I have to open and edit each file one at a time which is very time consuming.

Appreciate any advice, thanks in advance.

PS I use Sonar 5 Studio Edition