Task Sequence - Ask for Domain Join

Hi,

We need to ship a USB key with a MDT image + Task Sequence to deploy Windows 7.

The issue is that it will be shipped to multiple regional offices some of which have network connection to our corporate domain and some of which who don't.

So i would like during the deployment to have a window to ask users "Do you want to join this computer to the domain (Answer Yes if the computer is connected to ACME's corporate Network, otherwise select NO").

Then depending on their selection, try or do not try a domain join.

How can i achieve this?

Thanks