There are a number of tools that you can get for free and do it yourself.
Sam's Speech Decoder, combined with Flitskikker's IV Audio Toolbox and OpenIV allow you to extract the speech files from IV, automatically rename the speech files from V and import them into your speech file for use in IV.
I'm working on that right now, but as said above, there are a lot of lines used in IV that do not exist in V and vice versa.