如何仅在程序集发生更改时才使用MSBuild更新版本信息？

I have a requirement to install multiple web setup projects (using VS2005 and ASP.Net/C#) into the same virtual folder. The projects share some assembly references (the file systems are all structured to use the same 'bin' folder), making deployment of changes to those assemblies problematic since the MS installer will only overwrite assemblies if the currently installed version is older than the one in the MSI.I have a requirement to install multiple web se