I will use TSMuxer to pull out the subtitle track and then run it through BD2SUP and pull out just the forced tracks (I would move them into a 2:35:1 area if the movie was scope). I then remux the movie and subs with TSMuxer making sure that in either BD2SUP or TSMuxer that they are flagged as english, they should be by default but I double check so that when I watch the M2TS on either my WDTV's or my EP950, both devices set to load English subs by default, that they load at the appropriate time.
Hope that helps. And for reference when I try and view a movie with sub in MPC-HC they played in the correct spot but only displayed for a fraction of a second, I was pulling my hair out trying to figure it out, finally I turned on the WDTV and it displayed them PERFECTLY, lol.
Bill