The easiest way is to import the conjoint data using an accumulated data file.
In Lighthouse go to Field>Create Accumulated Data Template File. This file will show you the variable fields as they need to be imported (e.g. a field for ID number, for Version number and then fields for the responses). You can copy and paste from your fieldwork provider's data file into this template file and save it as a .csv file. Then in Lighthouse you go to Field>Accumulate Paper & Pencil Data to import that .csv file. Now your conjoint data is in Lighthouse just like if you had fielded the study yourself.