Public vs Private IP?

I just spun up a 2 node couchbase cluster using the enterprise free ami with a view to running some tests. However I've hit a roadblock. My dev environment is an VM on my mac. The couchbase cluster is on aws. They won't play nice.

What seems to be happening is I connect to the cluster using it's public IP (via the php sdk 1.1) and I can get meta info back eg getServers() works but I can't perform any actual operations like get() or set(). My best guess based on what getServers() returns is that the library is trying to use the internal 10.x.x.x addresses for the aws nodes which my mac can't route.

Is there any way round this? any way to tell the php library the external addresses of the servers?