There is a very short instruction for OS X of how to install on your mac in the Yenten OS X zip file.
Then when yentend is running you can use yenten-cli by executing yenten-cli from the OS X terminal.
For example if you want to generate an address:
./yenten-cli getnewaddress yentenaccount
This generates a Yenten address for you linked to an account named 'yentenaccount'
Copy/paste the account name and address somewhere for reference purposes.
To check if all works well you can try one of the faucets and let a faucet send some Yenten to your newly created Yenten address.
Then check your balance with:
./yenten-cli getbalance yentenaccount
If your balance stays at zero for a long time, this is possible because it can take hours for the blockchain on your mac to be fully synchronized if you run yentend for the first time.
Before shutting down your mac, don't forget to do
this shuts down the yentend nicely instead of just killing it.
Then when you want to use the yenten command line wallet again, don't forget to start yentend first with for example this command
./yentend -server -upnp -daemon
If you want to know what all those yenten-cli command options are, take a look at this wiki: it's for bitcoin, but it's mostly the same for Yenten:
https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list