I have to agree with the others that that's an odd program to write. If you want to hardcode the encrypted passwords, you can generate the encrypted passwords with a separate program or the command line or something and then hardcode them. But if you ever want to change the keychain password you have to go through that all over again, and to add any you have to generate the new ones and encrypt them and hardcode them in

If you use some kind of simple database (e.g. SQLite) you can add username/password pairs that are encrypted/decrypted on the fly. You still run into the "how do I hide the key for my encrypted passwords" problem-- you can use a keychain password as the key, and then if you change the keychain password have a loop that goes through and decrypts and reencrypts them (using the old and new passwords)