Nothing against third party plug ins, apart from I can't install them on the machine in question. Just thought Logic would come with lots of different panning plugs, can I achieve auto panning with any of the spread plug ins
Try the Modulation > Tremolo Logic plugin. As starting you can try any layering (looped) sound with "hard left right" settings:
2. Rate=1/8 (synced)
4. Smoothing=0 (you can try other values later)
Actually the "Autofilter" suggestion is perfect. You can do panning without filtering, set the timing as a musical value rather than just a time value, alter the amount of spread. the thing ROCKS!
And yes, Logic has almost every thing I can think of as a plug-n and some are more flexible that you think, with unusual features (like the extras in the tape delay: tape flutter, to help add a bit more realism, and the hidden distortion parameter).
I would suggest you take the time to at least scan the Plug-ins manual, you will be very pleased.