Microsoft.BizTalk.Component.Utilities.dll (or how to add reference to a dll wich is only in the GAC)

There are some DLLs wich are located only in the GAC, there is no physical file in our computer. Visual Studio does not allow you to add references to components in the GAC.

We have two alternatives:

1) Copy the file from the GAC to a physical file:
copy C:\WINDOWS\assembly\GAC_MSIL\
Microsoft.BizTalk.Component.Utilities\
3.0.1.0__31bf3856ad364e3\
Microsoft.BizTalk.Component.Utilities.dll

2) Unload the project, edit it and add manually the reference:

<itemgroup>
<reference include="Microsoft.BizTalk.Component.Utilities, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
<reference include="Microsoft.BizTalk.Pipeline, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
<specificversion>False></specificversion>
<hintpath>..\..\lib\Microsoft.BizTalk.Pipeline.dll></hintpath>
</reference>