Alternatively you can split it easily using Notepad and e.g. Vladimir's "SubSync". This simple and easy to use freeware utility covers .smi .srt and/or .sub format subtitles.
You can find it at
http://users.pandora.be/vlad/subsync/index.htm
On this website is also some documentation of how to use it.
Tip:
Leave the subtitlefile complete for the first CD (doesn't matter if the file is longer than the move) only check where the second part should start and create (e.g. in Notepad) a second file containing only the second part. Then use SubSync on that second part to adjust timings.