Synching iPhone wirelessly without iCloud

Running 10.6.8 on my mac, therefore don't have iCloud. Synching iphone with mac works fine with USB. The online article states that one of the conditions for syncing wirelessly is that "iOS device is plugged in to power". Meaning still plugged into the mac via USB?? Or into AC power?

If USB, the point of "wireless" is lost. I tried setting up wireless synching as explained in the article, plugged the iPhone into the AC power, and opened iTunes. iPhone doesn't appear. I hope someone can help, thanks.