<p>We have an old project written using Managed C++ syntax. I would like to propose to the team a reasonably pain-free (I don't mind some level of human interaction, I think I'm realistic in my expectations that we'll still have to do some work by hand) method of updating the existing code to C++/CLI syntax so that we can also add XML documentation (the project is a library into other projects and having documentation would be immensely useful).</p>

<p>So, are there any good tools out there to help with this? Or is it just a case of switching to the new C++/CLI syntax compiler and fixing errors as we go?</p>

Microsoft has a
tool
that will help a little.
Visual c++ blog post about it.
Here are a couple other resources I found useful when I made our switch
C++/CLI Migration Primer
Managed Extensions for C++ Syntax Upgrade Checklist
The Microsoft tool is just a start. there were many files that it could not convert.