Based on this slide from the netapp university and the following doc, it looks to me like NVE is OKM only.

Anyone have any information to support otherwise? 
On one of the slides here in the 9.1 new features document it says "Federal Internet processing standards 140...level 2 compliance, NSE systems and external KMIP server still required) 

I take that to have the unfortunate meaning that NVE cannot be used with an external key management server.

--Jordan