You should import the dump.sql file into your sqlite database then create a file in the model folder named after the table that is generated from the import.
If the mode is named correctly i.e. camel cased file name that matches the table name then all should be good and all you should need is a standard model class declaration in the file.
e.g. If the imported table is called new_imported_table then the file should be called NewImportedTable and the class declaration in the file should be
class NewImportedTable < ActiveRecord::Base
But you are heading for a fall! How are you going to get your imported table into your production and your test databases?
I would strongly suggest you use the rails generate model some_table_name command to generate the table and write a migration to import the data from a csv file, that way, if you convert the dump.sql into a csv file that gets added to a folder somewhere (I would suggest the database folder) then when you run rake db:migrate whether you are in your test, development or production mode you will get the data imported automatically for you and you won;t have to worry about your tests or your production environent not haviong the dumped data available to it and your job is done with regards to the imported table.