Try:

ssh-keygen -t rsa -N "" -f my.key

-N "" tells it to use an empty passphrase (the same as two of the enters in an interactive script)

-f my.key tells it to store the key into my.key (change as you see fit).

The whole thing runs without you needing to supply any enter keys :)

To send enters to an interactive script:

echo -e "\n\n\n" | ssh-keygen -t rsa