If you are playing a DVD from within MC you should be able to use the DVD menu to turn on Forced Subtitles, just as you would in a player.
If you have ripped the DVD to hard disk, you need to have an sidecar subtitle (i.e. srt) file that only contains Forced Subtitles, or a Subtitle file in a format that supports language tags on the subtitles. I think the SSA / ASS format supports language tags. Not sure, as I tend to use simple srt files. Depending on how you ripped the DVD, which tools you used, you could be able to rip the required subtitle file at the same time. You just need to find the content that is Forced English Subtitles, and not the English Subtitles, or save in a format that supports language tags. I believe MakeMKV has this capability, although there may be some issues.
There are also web sites around that can supply subtitles files, and some of them include only Forced Subtitles.
Google is your friend. The srt file needs to match your version of the movie / TV Show though, or the subtitles will get out of sync. You will find lots of discussion on providing subtitles for ripped programs on the web.
Did you read the
Subtitles Wiki article?
The forum has lots of discussion on using Subtitles with MC.
Search is also your friend.