[X4U] Photo metadata. Can it be edited?

[John Erdman]

Whenever I get photos of my grandson from my son, the photos are all  
dated with the camera default date. He's never taken the time to set  
the date correctly. I'd like to change the dates included in the  
metadata in the jpegs from their camera so that when it's cataloged  
in iPhoto the picture dates are roughly correct.

Beside IPhoto itself, and Get \info in the Finder, I've found several  
pieces of software that will read the data but none to edit the data.  
Ultimately I'd like to be able to either use an Apple script or  
Automator so I can handle the data changes in bulk.

Can it be done?  What OS X friendly software can you suggest?  Thanks.
John