Pretty sure it works with just passwords as well - see `JcloudsLoginLiveTest.testSpecifyingPasswordAndNoDefaultKeyFilesExist`. This runs a test with the equivalent of:

    brooklyn.location.jclouds.user=myname
    brooklyn.location.jclouds.password=mypassword
    brooklyn.location.jclouds.imageNameRegex=Debian 6

    --location jclouds:rackspace-cloudservers-uk

I haven't tested this manually.