What about something like 

```
TOKEN=$(curl https://discovery.etcd.io/new)
./etcd -name instance1 -peer-addr 10.1.2.3:7001 -addr 10.1.2.3:4001 -discovery https://discovery.etcd.io/$TOKEN
./etcd -name instance2 -peer-addr 10.1.2.4:7002 -addr 10.1.2.4:4002 -discovery https://discovery.etcd.io/$TOKEN
```

Alternatively, you can setup your own etcd instance as a bootstrapping node, and then use that for discovery. For example:

```
# setup etcd bootstrapping instance (single node is fine for bootstrapping)
./etcd -name discovery-etcd -peer 127.0.0.1:4444

# now point your new etcd cluster at this url
./etcd -name etcd1 -peer 127.0.0.1:4001 -discovery http://127.0.0.1:4444/<???>
./etcd -name etcd1 -peer 127.0.0.2:4002 -discovery http://127.0.0.1:4444/<???>
```