Not going to be able to finish the xml4com target tonight, but am now able to build xerces-c.dll and all the tests and samples with cl.
I did try building today with Microsoft's JVM and other than a failure to find a UTF8 encoder, it seemed to work okay.  Unless someone has a quick workaround, I'll just fallback to the default encoder and you should expect to constantly rebuild if you are compiling files with non-ASCII names on Microsoft's VM.  (Use of the default encoding would write out invalid XML files if there were non-ascii names).