American Express Membership Rewards - AMEX points for travel to Asmara

I've got over 400,000 AMEX (gold) points that I would like to use for tickets (up to 4) going to Asmara, Eritrea. Would want/need to fly on United/Lufthansa in July/August. As United does not participate with AMEX, would there be a method to transfer points to US Airways to make reservation via the Star Alliance?

Please see the post elsewhere in the forum entitled 'Amex miles to Lufthansa'. This contains your basic options to get MR points to miles you can use for *A carriers.