Add repository info to database.yml

development:
...
   repositories: 
       salesforce:
         adapter: salesforce
         username: USERNAME
         password: PASSWORD
         host: PATH_TO_WSDL_FILE

Then set up your model to use Salesforce:

module Salesforce
  class Lead
    include DataMapper::Resource
  
    def self.default_repository_name
      :salesforce
    end
  
    property :id, String, :key => true
    property :first_name, String
    property :last_name, String
    property :company, String
    ...
  end
end