if you need the compiled plugin, I managed to do it this way (with SD 4.4)
under Tools > Project Upgrade: compiler version 5, target fw .net 4.5.1
changed into .csproj to abs path to point to vvvv_45beta31.2_x86\lib\core\ like this, for example
C:\vvvv\vvvv_45beta31.2_x86\lib\core\
added this line into .csproj - after related error
EDIT:
I have also modified VVVVPIDNode.cs file like this
using VVVV.PluginInterfaces.V1;
using VVVV.PluginInterfaces.V2;
removing “simple” VVVV.PluginInterfaces