CDATA as api_method expected parameter

I’d like to know if there is any way to accept a CDATA block as a
parameter to an ActionWebService API method. I’d like to have
something like this,

class MyAPI < ActionWebService::API::Base
api_method :test, :expects => [:cdata]

The client would pass “” as the parameter
to the method, test.

Perhaps I need to specify :string as the expected type and somehow
tell the parsing library to interpret the string as CDATA?