Example for ANH (this was from my laserdisc transfer, you will need to change the frame numbers to sync with the DVD):
subtitle ("Going somewhere, Solo?",-1,470,71018,71056,"FranklinGotTDemCon",32,$ffffff)
subtitle ("It's too late.",-1,470,71184,71223,"FranklinGotTDemCon",32,$ffffff)
subtitle ("You should have paid him when you had the chance.",-1,470,71231,71289,"FranklinGotTDemCon",32,$ffffff)
subtitle ("Jabba's put a price on your head so large...",-1,470,71299,71370,"FranklinGotTDemCon",32,$ffffff)
subtitle ("...every bounty hunter in the galaxy will be looking for you.",-1,470,71376,71443,"FranklinGotTDemCon",32,$ffffff)
subtitle ("I'm lucky I found you first.",-1,470,71457,71495,"FranklinGotTDemCon",32,$ffffff)
subtitle ("If you give it to me, I might forget I found you.",-1,470,71561,71640,"FranklinGotTDemCon",32,$ffffff)
subtitle ("Jabba's through with you.",-1,470,71724,71764,"FranklinGotTDemCon",32,$ffffff)
subtitle ("He has no time for smugglers who drop their shipments...",-1,470,71795,71882,"FranklinGotTDemCon",32,$ffffff)
subtitle ("...at the first sign of an Imperial cruiser.",-1,470,71887,71926,"FranklinGotTDemCon",32,$ffffff)
subtitle ("You can tell that to Jabba. He may only take your ship.",-1,470,72015,72106,"FranklinGotTDemCon",32,$ffffff)
subtitle ("That's the idea.",-1,470,72163,72189,"FranklinGotTDemCon",32,$ffffff)
subtitle ("I've been looking forward to this for a long time.",-1,470,72203,72287,"FranklinGotTDemCon",32,$ffffff)
You may adjust the font, size, colour and positioning to your taste (and replace ' with ’ where appropriate).
For subtitles in a separate file, get VSFilter and use the plugin for AVISynth or VirtualDub.