2016-11-24 11:45 AEST by Arthur Barrett - Apparently you can use the PDBSTR tool from the Microsoft Debugging Tools to insert a 'source 
string' so that the debugger can find/download the sources, directly from CVS if needed.

PDBSTR tool:
https://msdn.microsoft.com/en-us/library/windows/hardware/ff558874(v=vs.85).aspx

MS even has plans to natively support CVS in the future:
https://msdn.microsoft.com/en-us/library/windows/hardware/ff560090(v=vs.85).aspx

But you don't actually need to wait for that...
https://msdn.microsoft.com/en-us/library/windows/hardware/ff560147(v=vs.85).aspx