1. Download XviD4PSP and install the application on your computer.
   NOTE: You need to register with the website and login before you can download the XviD4PSP. Search for the file on the Internet to download from one of the mirrors if you don’t want to go through the hassles of registration.
   When the installation is finished, run XviD4PSP from the start menu or desktop shortcut. The main window should look like this:

   

2. Open the MP4 file into which you want to hardcode the subtitles from File -> Open File….

   
   The format of the video file should be detected and default settings should be properly selected in the Format: panel. You can change some of the format settings if you want to.

3. XviD4PSP showed me the following message window on Windows Vista(did not get it on Windows XP) and continued reading the information from the input file after I clicked the Yes button.

   

4. Add the subtitle file for this MP4 video by going to Subtitles -> Add menu.
   
5. Select the directory where the output file should be stored by clicking on the Save button on the toolbar.
   
6. You can now repeat Step 2 to Step 5 if you want to add more subtitle hardcoding jobs to the queue. When you have added all the MP4(or even AVI) videos to the queue, you can click the Encode button on the toolbar to begin the encoding/subtitle hardcoding process.
   
7. I tried my best to keep the encoding settings as close to the actual format of the input file as possible. But the re-encoding + hardcoding process still took almost as long as the play time of the video file(i.e. 37 minutes for a 37 minute video). I am still trying to optimize the process. You get the following window with brief information once the encoding is complete.
   
   You can click the Info button to view detailed information. Below is an example MP4 video file that I have hardcoded the subtitles into.
   

XviD4PSP is an excellent tool for encoding, re-encoding and subtitle hardcoding jobs.

Tutorial found on http://beans.seartipy.com/