Through the NSX UI. According to the VMware NSX Documentation2, you can deploy NSX Edge nodes as virtual appliances through the NSX UI by clicking Add Edge Node and providing the required information.
The other options are either outdated or not applicable for virtual NSX Edge nodes.
https://docs.vmware.com/en/VMware-NSX/4.1/installation/GUID-E9A01C68-93E7-4140-B306-19CD6806199F