Register assembly

I would like to add assembly closedxml.dll to SQLserver:

http://closedxml.codeplex.com/

It has referencing some other windows dll, like:
System.Drawing
System.Windows.Forms
WindowsBase

and so on...

When I register assembly closedXml.dll (Net. 3.5 version since SQL2008 doesn't support higher) why it doesn't register automatic all referenced assemblies? They are all from .NET 3.5 and every server has this NET installed (beside newer versions).

What is the best way to install this closedXll into sql server?

br, Simon