Prompt to join domain during mini setup?

[MJC68]

Has anyone figured out the sysprep.xml to make this happen? In sysprep for XP this was a piece of cake, something like domain= (blank) in the .inf, now I have to hardcode a domain name in the XML and it joins automatically without prompting, the trouble is I WANT the prompting, otherwise I will either need a different image for each domain or I have to give up and have it just join a workgroup then expect the user to join the domain manually at first logon.