fotofono, depending on the kind of result you're after, you may want to consider a sidechain. I'm pasting text from a previous post I did where someone wanted to be able to create a stutter effect (with mute) on a vocal track. It may apply to what you're trying to do.
Here's how:
On the vocal track you want to create the stutter effect, insert a noise gate.
On the noise gate plug-in window, look for the sidechain input (top right).
Pick 'Bus 32' for example, or a bus that you don't have in the environment window.
Pick an empty midi track in the arrange window, insert an EXS piano or any other Audio Instrument (something with good attack works best). Assign it's output to Bus 32.
Since bus 32 is not in the environment window (make sure it isn't), it won't output any sound to the main outs, and you won't hear that Audio Instrument you've just inserted. Nevertheless the audio is still being routed within Logic, and will affect the SideChain of the noise gate, which is what you want to create the stutter.
Sequence the rhythm for the stutter into the midi track (you won't hear the Audio Instrument, but you should hear the vocal track stuttering to your midi track playing), do any quantizing you want, etc, and the noise gate will follow the notes.
You can also tweak the Noise Gate of course, to ease the threshold of the stutter, etc.
Even if it's not what you're after, you may find it's a really useful tool for many kinds of results.
Regards,
Luis
www.logicprocorner.com