No, that's not possible. Live Mesh is designed to sync all content in the Mesh folder, so a deletion, addition, or change on a single PC gets propagated to the Mesh pretty quickly.
I suggest that you only place the file in the Mesh folder after it is saved in a working folder that lives outside the Mesh folder. It would be a pain, but while that PC is online and logged into Mesh, the folder will sync to the Mesh.
-steve
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