<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <UsingTask AssemblyFile="C:\CustomTasks\MyTask.dll" 
              TaskName="MyTask.MyTouch"/>
   <ItemGroup>
      <FichierSrcCs Include="*.cs"/>
   </ItemGroup>
   <Target Name="TouchTheCsFiles" >
      <MyTouch Files= "@(CsSrcFiles)"/> 
   </Target>
</Project>