Using an Address Book custom label on a printing label I have a custom label in my Address Book cards (to indicate the name I'd like to appear on a label, e.g. The Smith Family). 

I'm on Lion (so that's Address Book version 6.1 on Mac OS X 10.7.2). 

When I go to print the labels, File > Print > Mailing Labels I can't change it from using the Name (Prefix - First Name - Surname). 

Before I set off trying to export this to a mail merge and use a much more complicated method, is there a way of doing this within Address Book? 

I found this hack which suggests adding the label as the Company Name, because that is an option to print, but some of the people have actual company names, so that isn't going to work for me.
When printing labels, I find a good technique is to make a new Address Book group. Here's a technique that might work, depending on the size of the job. 

Duplicate a contact with copy/paste, and drag the copy into the label printing group. Edit the card so the name fields are blank, and set the first name to be "The Smith Family". When you're done making the label changes, select the group and bring up the printing UI, which will print the contacts in the group.

When you're done printing, delete the contacts from the label printing group, then delete the group, and your original contacts remain intact.