Launch System Profiler. Choose Apple > About This Mac > More Info.
Identify your iPod In System Profiler, go to Hardware > USB and locate the iPod or iPhone you're using. Look up the Manufacturer ID (0x05ac (Apple Computer, Inc.) and Product ID (0x1291 for my iPod touch)
Launch Terminal. This requires shell access.
Find the utility. Change directories to /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/Resources/.
Run reenumerate Give it one argument: the vendor id followed by a comma followed by the product id, e.g. ./reenumerate 0x05ac,0x1291
Wait. iTunes will reload your iPod or iPhone and sync it.