The command you are looking for is establish_connection. You might want to look at the rails rdoc. Search for "Connection to multiple databases in different models" in http://api.rubyonrails.com/classes/ActiveRecord/Base.html.
eg:
class SomeModelDB1 < ActiveRecord::Base self.establish_connection("db1") end
class SomeModelDB2 < ActiveRecord::Base self.establish_connection("db2") end
database.yml db1: adapter: mysql database: somedb username: user password: pass host: localhost socket: /tmp/mysql.sock db2: adapter: mysql database: somedb2 username: user password: pass host: remotehost
