I have shot multicam concerts locking up timecode by beaming wireless audio SMPTE timecode to all cameras and recording it on Ch 2, but I can tell you it was a big hassle and a waste of time.
My recommendation for multi-camera shoots is to either:
1. Use TOD (Free Run) Timecode
TOD (Time of Day) timecode is a switchable option on some recent camcorders. With this option, you can synchronize multiple cameras, then each camera can start or stop at will, and the timecode always reflects the current time, not the tape position, so the shot can always be matched to the other cameras.
The TOD timecode option on the Canon XL2 is shown near the end of the XL2 Feature Tour video on this page:
Here is a clever article by Chris Hurd on using Free Run Time Code for multicam shoots:
2. Use Sync Point and Rewrite Timecode in post
If your camcorders do not have the TOD timecode option, the next best thing is to use a "sync frame".
Each time the cameras roll, shoot a sync frame, which could be a slate with clapper, someone clapping their hands once, or some other visual or sound cue that you can identify in all camera shots as the same frame. You’ll need to do this again each time you stop, then restart the cameras. It’s best if this sync point is visual and sound, since you can scrub picture to get close, then zero in on the spike in the audio waveform which is far more accurate (48,000 samples per second) than picture (24 – 29.97 frames per second).
Sometimes the sync frame is natural, like when shooting a live musical event, the beginning of each song could serve as a sync point.
In this case, it’s important to have wild sound (built-in camera mic) live for all cameras, since you’ll be able to easily fine-tune sync between the different cameras by emilinating the echo on the audio tracks.
Then, in your editing software, you can match the sync frames and all else should be hunky-dory. In some software, you can actually rewrite auxillary timecode for some clips so the timecode matches the A camera exactly. If you do this, don’t rewrite the primary timecode track, just the auxillary, or else you lose the ability to media manage, batch capture, etc.