The Keychain Services Integration extension allows you to store your Conkeror "... website usernames and passwords in Apple's Keychain Services, just like Safari and other browsers do on OS X. This allows you to use the same stored logins in any browser that uses the Keychain. It also allows you to take advantage of the security features of Keychain Services such as auto-locking when the screensaver is activated."

The extension works quite well with Conkeror and is easy to install. Grab the .xpi file and edit install.rdf. Next, enable the Xulrunner password management service by adding the following to your rc:

session_pref("signon.rememberSignons", true);
session_pref("signon.expireMasterPassword", false);
session_pref("signon.SignonFileName", "signons.txt");
Cc["@mozilla.org/login-manager;1"].getService(Ci.nsILoginManager); // init

Once activated, Keychain services integration will override the Xulrunner password manager, giving you automagic access to your OS X Keychain items when you visit relevant sites.