Generating XAC silently

[achu]

During the development phase, we have different people involved in DTD authoring, CSS editing and macros coding. Each person has his/her own tool to edit the files without using XMetal Developer.
Every time those files got updated, we need to go through XMetal Developer to include those updated files again in order to compile into XAC file.
I just wonder if there is "silent" way, for example through command line,  to run the compiling process so that the xac update processes can be set up automatically. 

Version: XMetal Developer 5.1

[Derek Read]

The only thing I can think of at this time is to generate a ZIP archive containing everything that needs to be in the XAC (we don't provide this either, but there are lots of ways to generate a ZIP at the command line) and then rename that file with a .XAC file extension.