right I've got passed this error (x_auth_Mode needed a lower case m) but now get "Failed to validate oauth signature and token."
My signature looks looks this, I'm pretty sure this should be working as worked with the test case example off the documentation POST&https%3A%2F%2Fapi.twitter.com%2Foauth %2Faccess_token&oauth_consumer_key%3DubbJyw4HUpnxzUaVjpC0pw %26oauth_nonce%3DlUUgQKTbYcFL6Gnwuv1J6sgx95qukm0AmiQMJskFnJ %26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp %3D1276856124%26oauth_version%3D1.0%26x_auth_mode%3Dclient_auth %26x_auth_password%3Dxxxxxx%26x_auth_username%3Dxxxxxxx I then sign this with the key which is the consumer secret followed by &
