Exact splitting of MKV file

I have a series of DVD's where the episodes are not separated from each other. After ripping to MKV I need to cut where one episode ends and the next starts.

This can only be done with slight reencoding and generation og new keyframes in the selected area. That is acceptable.

SolveigMM Video Splitter for PC can do that but works very slowly and erraticly on my VMWare Fusion XP virtual machine.

So is there a Mac tool for this - or at least a reliable PC tool?