Hi,
What I have found is that there is no single tool that can accurately script a conversion of every possible configuration out there. There are so many variations in network topology, naming conventions, etc. that properly converting all the behavior of previous technologies is difficult.
If you have less than 50 or so virtual servers, you'll be better off doing the conversion by hand. If you have more than that, then a script can save time, but I'd still be prepared to do a fair amount of manual tweaking. I wrote a script to convert ~1600 virtuals from a CSM (not CSS) configuration, and it was highly dependent on known elements of the customer's config to work properly (so it can't be reused for another site), and even then I had to manually redo stuff.
Given enough time, a script could probably be developed to handle generic configs, but again it's usually not worth the effort for typically sized configs.
Denny