Dealing with a non-RESTful service

def get_kindle_sales(cs_user,cs_pass)
    session = Mechanize.new
    session.user_agent_alias = 'Mac Safari'
    session.get 'https://www.amazon.com/ap/signin?openid.assoc_handle=amzn_dtp&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.return_to=https%3A%2F%2Fkdp.amazon.com%2Fself-publishing%2Fsignin%2Freturn&marketPlaceId=ATVPDKIKX0DER&pageId=amzn_dtp&openid.mode=checkid_setup&openid.pape.max_auth_age=0&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0'
    form = session.get('https://www.amazon.com/ap/signin?openid.assoc_handle=amzn_dtp&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.return_to=https%3A%2F%2Fkdp.amazon.com%2Fself-publishing%2Fsignin%2Freturn&marketPlaceId=ATVPDKIKX0DER&pageId=amzn_dtp&openid.mode=checkid_setup&openid.pape.max_auth_age=0&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0').
      form_with(:name => 'signIn')
    params = {'email' => cs_user,  'password' => cs_pass}
    %w(appActionToken appAction openid.pape.max_auth_age openid.ns openid.ns.pape pageId openid.identity openid.claimed_id openid.mode openid.assoc_handle openid.return_to).each do |field|
      params[field] = form[field]
    end
    session.post('https://www.amazon.com/ap/signin', params)
    response = session.get('https://kdp.amazon.com/self-publishing/reports/transactionReport?_=1326589411161&previousMonthReports=false&marketplaceID=ATVPDKIKX0DER')
    hash = JSON.parse(response.body)
    kindle_units = hash['aaData'][0][5]
end