A better solution would be to manually add the PC to the domain (either way this will take a while over a VPN but as long as the DNS settings are right, it should work, I've done it myself before).
Then afterwards you can move the profile manually. If this is a Windows XP client PC, there's a tried and tested way of doing this:
http://msmvps.com/blogs/clustering/archive/2004/10/06/15096.aspxFailing that, a hardware VPN to VPN solution would work - this is how I did it. This holds up a Lan to Lan tunnel between the two sites and the PC is therefore not involved in the connection. Whether the SBS Connect Wizard would work over it is another matter.