step 1.Go to https://dev.twitter.com/apps
step 2.Create app(fill up the form)
step 3.Change permissions if necessary(depending if you want to just read,write or execute)
step 4.Go To API keys section and click generate ACCESS TOKEN.
5 years late to answer :)
Now you have these tokens which is all you need.
'oauth_access_token' => Access token
'oauth_access_token_secret' => Access token secret
'consumer_key' => API key
'consumer_secret' => API secret