George,

It's easier than you think.

I called Texas Department of Transportation
Vehicle Titles and Registration Division {(512) 465-7611} and asked this question for you.

If you buy the vehicle, the owner will fill out and sign the back of the title.  He must also provide you a bill of sale.  For the sale to be legal, the vehicle registration must be current.  You'll retain the Texas licence plates (they transfer with the vehicle).   You'll have 20 business days to drive the van back to Colorado and have it titled and registered there.  According "John" at TXDOT, your current car insurance policy should cover you for the 20 day grace period you have to title and register the van in your own name, but check with your insurance agent.   If you don't title/register it in your name within the 20 days, you face penalties payable to TX.

Hope this helps.  Let me know if I can provide any more info.

Jim Bowen
Round Rock, TX
'88 Vanagon Wolfsburg (LOLA)