it depends on what control surface you have. Some are easier to change midi channels and some are a pain to change. If you can tell us what controllers you have we can go about giving you the right info.
Grab the latest version of Trakor Pro that was just released (1.2.1) it has support for multiple TSI’s running independent of one another so you don’t need to change midi channels or anything like that
Yeah, for the channel change, you have to change both the transmitting channel from within the device itself, and also the recieving channel for those commands within Traktor. How easy this is to do depends on the devices themselves, i’d think it shouldn’t be too hard with the Korg stuff they make a lot of MIDI devices and keyboards, but not so sure about the Berry.
Other alternatives as said are to use a small translator program like the ones Bento mentioned to accomplish the same.
The new Traktor 1.2 does have support for multiple MIDI maps and would be great in this situation, but if you have any gigs coming up soon I would hold off, because most users are reporting that their current MIDI maps have needed significant reprogramming to work correctly.
you can change the korgs’ midi channel globally using the korg editor software. i’d take a screenshot if i weren’t at work, but it’s really not hard to find. after changing the channel and storing the settings, you have to remap your controls in traktor.