Home Loan for Foreign National in US on O1 Visa?

The buyer was brought over here by the U.S. government to work for one specific company because he had unique skills / abilities that no one here had and he has a 01 Visa (lets him work for this one company - if he gets fired before his permanent green card comes through I guess he has to go back to the UK), he has good credit in the UK - but no credit to speak of here in the US.  He has had 3 mortages over there.  He has "permanent employment" status with his company and is only a few months way from having a permanent green card - I guess he's been here for 16 or 17 months now. 

His down payment and income have all been verified, at this point it's all about the non-US credit history and his greencard status.  All other contingencies on the contract have been removed.  He was preapproved when the property went into escrow, but because of his Visa status I guess they will not fund the loan.

Do you have any suggestions or referrals for a loan that might be able to go through for him?  Has anyone been in this situation and how did it turn out?  Sale price is $675,000 with 20% down.  Thanks for any insight!