While MPLAB X fully supports pre-built projects, the preferred method to program from a hex file is to use the MPLAB IPE application
Because MPLAB® X IDE is project based, it is not possible to simply import a hex file as was done in MPLAB 8. However, the same result may be achieved by creating a pre-built project. This will create a project "wrapper" around the hex file so that it may be used the same way as a hex file built from within a project. The main difference is that you will be able to program a target without being required to build the project since the hex file already exists.
Video - Importing and Programming a Pre-Built .hex file in MPLAB® X
This video shows the steps to import a pre-built .hex file and program it into the target device using MPLAB®X.
|Menu:||File ▶ New Project…|
Launch the new project wizard
Once you click Finish the project has been created. It will now be open in the project tree.