I have a lengthy movie (2hrs 40 min) that I would like to rip to 2 XviDs with Handbrake. However, I'd also like to create a subtitle file for each half. How would I go about doing this?

I know Handbrake only allows you to permanently burn the titles in to the picture. What program could I use to split the subtitle file where I need to (by chapter), or rip on a chapter by chapter basis?