What is MTC (Midi Time Code)?
MIDI Time Code (MTC) is a sub-protocol within MIDI, and is used to keep 2 devices that control some sort of timed performance (ie, maybe a sequencer and a video deck) in sync. MTC messages are an alternative to using MIDI Clocks and Song Position Pointer messages. MTC is essentially SMPTE mutated for transmission over MIDI. SMPTE timing is referenced from an absolute "time of day". On the other hand, MIDI Clocks and Song Position Pointer are based upon musical beats from the start of a song, played at a specific Tempo. For many (non-musical) cues, it's easier for humans to reference time in some absolute way rather than based upon musical beats at a certain tempo.
In order to use MTC with the MPC your other device needs to be compatible with MTC. Most of your recording packages are (like Cool Edit Pro) and most of the Midi/Audio packages are (Cubase, Cakewalk, etc). Many or your hardware recording devices use MTC like the Akai DPS series.
MTC operates very similar to SMPTE in where it provides an absolute time reference from the master device. This is different from midi clock in which midi clock provides only relative time (24 pulses per quarter clock), basically telling a slave device when to start, stop and 'tempo' information. Where MTC is different from SMPTE is that it stays completely as digital data transferring over standard midi cables, even using one set of midi ports on the MPC. However, you do not want to transmit other midi data on the same ports and cables as MTC because of the volume of data and especially since you need uninterrupted flow of sync signal for timing.
Using MTC is relatively easy. Decide which device is going to be master and which are going to be slave. Set up master to output MTC and slave to receive. The rest of the settings are trial and error, like start time. You do not want time zero (or the start of the recording) to be right when you hit play, since you need a few seconds for all of the time to 'spin up' and lock. Also remember to set tempo everywhere needed since MTC does not transmit tempo data and syncing may not be so smooth if it is spending all of it's time catching up.
I've only scratched the surface of using MTC. I'll try to go into more detail later.