I found it rather by accident today. I have played with all the neat features of iOS 7 but stumbled upon this one in an unusual place.

Tap on your favorites in the phone book. Tap on the (I) for information about your favorite and tap Edit, tap on Vibration. Scroll down to the bottom and under 'Custom', tap 'Create New Vibration'. It now allows you to tap the screen for dits and dahs and have your custom morse code vibrate when in silent mode.

I could not find any way to make a custom vibration in Settings/Sounds. Go figure.

Pretty neat and ham friendly. Works great on my iPhone 5, waiting on my iPhone 5S to be delivered next week.

73...bruce