I have downloaded vobsub subtitles for a movie, I'd like to add them to a DVD video I am making.

Using tcextract of transcode I can obtain the raw subtitle stream.
Code:
tcextract -i english.sub -x ps1 -a 0x20 > subs-en
Now I have the subtitle raw stream and the mpeg file made using mplex -f 8.
How can I mux them?

Notes:
spumux does not work as it accepts only pictures or texts, not directly a raw mpeg stream.
I can extract the subtitles via subtitle2pgm, but I would lose the colours and it seems a waste to extract the subtitles from a subtitle stream to make another subtitles stream.

Any advice?