SSIS 2012 Assembly Reference with relative Hintpath?

Hi -

I have several SSIS packages with script tasks that reference a custom C# assembly. When I add the assembly reference to a Script task, VSTA puts the full path into the .dtsx file, e.g.

    <Reference Include="MyCorp.SSISHelper">
      <HintPath>C:\tfs\Dev\Apps\Src\Rpt\SSIS\SSISHelper\bin\Debug\MyCorp.SSISHelper.dll</HintPath>
    </Reference>

I have tried closing the package, then manually editing the .dtsx file to change the assembly's Hintpath to a relative path, e.g

    <Reference Include="MyCorp.SSISHelper">
      <HintPath>..\SSISHelper\bin\Debug\MyCorp.SSISHelper.dll</HintPath>
    </Reference>

The SSIS project (with all .dtsx files) is at:

C:\tfs\Dev\Apps\Src\Rpt\SSIS\SSISProject\SSISProject.dtproj

When I edit the script again on VSTA, the assembly reference is undefined and the path shows as blank.

Is is possible to have a relative Hintpath for an assembly in the .dtsx file?

If so, is it also possible to put the build config in the Hintpath, e.g.

    <Reference Include="MyCorp.SSISHelper">
      <HintPath>..\SSISHelper\bin\$(Configuration)\MyCorp.SSISHelper.dll</HintPath>
    </Reference>

Thanks!